2019 - - - - - - - - - - - - - - - - - - - - - -
- - - -
Soil
stabilisation by water repellency under no-till management for soils with
contrasting mineralogy and carbon quality
No-till soil management is
common around the globe, but the impacts on soil structural quality varies
depending on cropping practice and inherent soil properties. This study
explored water repellency as a driver of soil stabilization, as affected by
soil mineralogy, granulometry and organic carbon quality in three Mollisols and
one Vertisol under no-till management and with different levels of cropping
intensity. The studied soils were located along a west-east textural gradient
in the northern part of the Pampean region of Argentina. Cropping intensity treatments
evaluated in each one of the soils were: Poor Agricultural Practices (PAP)
close to a monoculture, Good Agricultural Practices (GAP) involving a diverse
crop rotation and more targeted inputs, and the soil in the surrounding natural
environment (NE) as a reference. NE had the greatest aggregate stability (MWD)
of all cropping intensities, with GAP being more stable than PAP for Mollisols
and PAP being greater than GAP for the Vertisol. This trend matched the
Repellency Index (Rindex), with greater Rindex associated with greater MWD, including
the difference between the Mollisols and Vertisol. However, the persistence of
water repellency, measured by the Water Drop Penetration Time (WDPT) test
followed the trend NE > GAP > PAP regardless of soil type. The increases
in Rindex and MWD were related to higher intensification as measured by the
Crop Sequence Index, and decreased with greater soybean occurrence in the
sequence. Both WDPT and Rindex were closely related to aggregate stability,
particularly for Mollisols. These results highlight the importance of
considering the inherent soil characteristics texture and mineralogy to
understand aggregate stabilization mediated by water repellency. Good
correlations between soil water repellency, organic carbon fractions and
aggregate stability were found. Under no-till, crop rotations can be altered to
increase soil stability by inducing greater water repellency in the soils. The
findings suggest that water repellency is a major property influencing soil structure
stabilization, thus providing a useful quality indicator
Nitrogen
balance in a plant-soil system under different cover crop-soybean cropping in
Argentina
Cover crops (CC) provide many benefits for the soil and
the following crop but their effects on nitrogen (N) release and balance in
continuous no-tillage soybean (Glycine max
L. Merr.) production are little known. Estimation of the biological nitrogen fixation (BNF) in intensive agricultural systems under
soybean is essential to understanding the N dynamics and to determining the
balance and crop demand. This study (2006–2011) was performed on a Typic
Argiudoll under no-tillage in the province of Santa Fe, Argentina. The aims
were to study the effect of fall winter CC, such as wheat (W), oats (O), oats + vetch (O +
V) and vetch (V), on the yield and N-content of the following crop
(soybean) and to quantify the contribution of the BNF and N-balance. Three
methodologies were used for BNF estimation: 1) a linear regression model
between BNF and N-uptake by soy- bean; 2) the natural 15N abundance
in soybean and 3) the average BNF in the Pampa region. Gramineous CC developed
more dry matter than pure legume species, with intermediate values for the gramineous-legume
mixture. Biological fixation provides
60–70% of absorbed N, according to the estimation method. Within the rainfall
range of 500–1000 mm during the soybean cycle, CC did not affect the grain
yield or soybean dry matter production. The partial N-balance was always
positive, with differences between the techniques used for BNF estimation.
Cover crops have contributed to the positive soil N-balance. Gramineous CC
stored 22% more N- content in the soil surface layer than the others. Cover
crops showed 15% higher index of N-stratification on the
surface compared to the control soil. Using CC would be an efficient
alternative to produce biomass and to supply
N to the soil for the subsequent crop
Landriscini
M.R., J.A. Galantini, M.E. Duval, J.E. Capurro. 2019. Nitrogen
balance in a plant-soil system under different cover crop-soybean cropping in
Argentina. Applied Soil Ecology 133:124-131. doi: 10.1016/j.apsoil.2018.10.005
2018 - - - - - - - - - - - - - - - - - - - - - -
- - - -
Cover
crops in the Southeastern region of Buenos Aires, Argentina: effects on organic
matter physical fractions and nutrient availability
In the Southeastern region of Buenos Aires province,
soybean monoculture has led to a decline in soil organic matter (SOM) levels in
soil, mostly the labile fractions. The reduction of SOM has a negative impact
on the soil environment. Cover crops (CC) constitute an alternative to maintain
or improve SOM levels. The aim of this study was to determine the effect of oat
as CC on (a) the SOM dynamics and (b) the availability of macro- and
micronutrients in a representative soil of the Southeastern region of Buenos
Aires province. Total organic carbon (TOC) and nitrogen (TON), as well as their
labile and mineral-associated fractions, and macro- and micronutrient
availability were determined. The treatments were soybean monoculture with and
without oat as cover crop. The increases in SOC and TON were 22.7% and 11%,
respectively, when CC was included to the soybean monoculture. These increases
were observed mostly in the labile fractions, with increases of 61.3 and 38.7%
for the particulate coarse organic carbon (PCOg) and particulate fine organic
carbon (PCOf), respectively, and 79.2% for the particulate coarse organic
nitrogen (NOPg). Regarding the nutrients, an increase of 47.6% was observed in
manganese (Mn) in the first 5 cm of soil depth, and a decrease in phosphorous (P)
availability in the same soil layer due to its consumption and retention by CC.
It can be conclude that CC presented a surface soil effect on the dynamic of
SOM, increasing C, N, and available Mn contents, but decreasing soil P
availability
Oat, Soybean monoculture,
Particulate organic carbon and nitrogen
Beltrán M.J., H. Sainz Rozas, J.A. Galantini, R.I.
Romaniuk, P. Barbieri. 2018. Cover crops in the Southeastern region of Buenos
Aires, Argentina: effects on organic matter physical fractions and nutrient
availability. Environmental Earth Sciences 77:428. DOI:
10.1007/s12665-018-7606-0.
Labile
soil organic carbon for assessing soil quality: influence of management
practices and edaphic conditions
Soil organic carbon (SOC) is a complex set
of pools, and to understand its dynamics it is necessary to know which of these
pools are sensitive to the edaphic and climatic conditions or the agricultural
practices, or to both. The objectives of this study were to evaluate the
relationships between permanganate oxidizable C (POX-C) and various soil
organic carbon fractions in different land-uses and soil types, and to examine
whether the POX-C fraction is sensitive to different agricultural management
practices in soils under no-tillage. Three treatments were identified at four
sites located in the Argentine Pampas region: two different agricultural
scenarios in terms of crop rotation, fertilizers and use of agrochemicals (Good
Agricultural Practices and Poor Agricultural Practices, GAP and PAP,
respectively) and an undisturbed natural (NE) environment adjacent to the
agricultural sites as the control treatment. The following organic fractions
were quantified: SOC, coarse and fine particulate organic carbon (POCc
and POCf, respectively), hot water and acid extractable organic
carbon (HWC and HAC, respectively) and POX-C. Soil POC values ranged from 0.46
to 7.29 g kg−1, HAC values ranged from 1.50 to 6.73 g kg−1, HWC
values ranged from 0.20 to 1.10 g kg−1 and
POX-C values ranged from 0.41 to 1.04 g kg−1 soil,
POCc being the most variable fraction (CV=72%) and POX-C the least
(CV=22%). Soil POCc and POCf at 0–10 cm, and POCc
at 10–20 cm
were largely explained by management practices with a component of variance
>50%. The relationship between POX-C and SOC was generally stronger (R2=0.76–0.92)
than POX-C with other organic fractions and where depth and site factors have a
greater influence on this relationship than management practices. Among the
labile fractions, the most sensitive indicators of soil quality in agricultural
soils were POCf and HWC, which displayed the highest F-statistic
values. Despite the dilute solution used (0.02 mol L−1 KMnO4)
the POX-C demonstrated limited sensitivity to different agricultural practices.
However, this methodology could be used to estimate SOC regarding site
conditions and depths. The POCf was the fraction most affected by
agricultural practices, indicated by high relationships with both the soil
physical attributes (macroporosity, bulk density, and density, volume and
stability of aggregates) and the agronomic parameters (soybean and maize
yields).
Permanganate oxidizable carbón,
Particulate organic carbón, Hot water extractable carbón, Acid extractable
carbón, Agricultural practices
Duval M.E, J.A. Galantini, J.M. Martínez, F. Limbozzi.
2018. Labile soil organic carbon for assessing soil quality: influence of
management practices and edaphic conditions. Catena 171 316-326. DOI
10.1016/j.catena.2018.07.023
Contribution of nitrogen
mineralization indices, labile organic matter and soil properties in predicting
nitrogen mineralization in Mollisols
The objectives of this study were i) to measure the nitrogen (N)
mineralization potential; ii) to evaluate N mineralization indices and labile
soil organic matter (SOM) fractions, and iii) to analyze their
interrelationship with soil properties for predicting the potential N
mineralization in Mollisols under no-tillage of the Argentine Pampas. Potential
N mineralization pool was determined by aerobic incubation of soil samples from
0-20 cm depth at 25°C for six drying and rewetting cycles over 21-24 weeks. The
data were fitted to a first-order exponential equation to determine the
potentially mineralizable N at a variable (N0) and at a fixed constant rate
(N0kf). Several N mineralization indices, labile organic fractions and soil
properties were determined. A broad range of values were found for N 0
(29.9-220.7 mg kg-1) and N0kf (26.9-172.4 mg kg-1). A
close relationship (P<0.001) was found between N0 and N 0kf with a high
coefficient of determination (R2=0.94). High R2 values
were found for predicting N0 and N0kf using the principal component as regress
variable. Total and labile organic fractions and sand content, explained the
majority of the variance. No single N mineralization index, labile organic
fraction or soil property can accurately predict the potential N mineralization
at a variable and at a fixed constant rate. The potential N mineralization pool
may be controlled mainly by the variables related to the size of SOM and some
labile fractions, i.e. soil organic C (SOC) and N (SON), soluble carbohydrates
(CHs) and fine particulate organic N (fPOM-N) in these Mollisols.
doi: 10.4067/S0718-95162018005000401
A rapid method for
estimating labile carbon and nitrogen pools in Mollisols under no-tillage
The objective of this study was to adapt the partial
chemical digestion method for estimation of labile soil organic matter pools by
evaluating the effect of different digestion times in Mollisols of the
Argentine Pampas. The soils were sampled from nine agricultural fields under
notillage at the 0–20 cm depth. A chemical method was performed through partial
soil digestion with dilute sulphuric acid at 100°C on the basis of four
digestion times: 1 (Nd1), 2 (Nd2), 4 (Nd4) and 6 (Nd6) hours. Soil organic
carbon (C) and nitrogen (N) fractions were determined. The extracted organic N
(Nd) ranged from 0.076 g kg-1 to 0.273 g kg-1, with a
mean of 0.154 g kg-1. Statistically, the means for each digestion
time indicated highly significant differences (P = 0.008). High correlations
were found between Nd for different times and labile C and N fractions.
However, the best fit prediction was observed between Nd2 and soil total
carbohydrates (CHt), with a high coefficient of determination (R2 =
0.94). Partial chemical digestion for 2 h can be used as a rapid indicator to
accurately predict CHt. Because of its speed and simplicity, this method may
also be useful for rapid soil quality assessments.
Martínez
J.M., J.A. Galantini, M.E. Duval. 2018. A rapid method for estimating
labile carbon and nitrogen pools in Mollisols under no-tillage. Archives of
Agronomy and Soil Science 64 (9) 1321-1327,
doi: 10.1080/03650340.2017.1422123
Download ResearchGate Journal Google
Drive (in ENGLISH)
Estimating soil organic carbon in Mollisols and its particle-size fractions by loss-on-ignition in the semiarid and semihumid Argentinean Pampas
Recent interest in soil quality assessment underscores
the need for an accurate measurement of soil organic carbon (OC) and its labile
fraction, i.e. particulate OC. The loss-on-ignition (LOI) method has been
proposed as a rapid, inexpensive and accurate method for estimating OC. The
objectives of this study were i) to test the LOI method for soil organic matter
(SOM) and particulate organic matter (POM), and ii) to evaluate the use of an
adequate conversion factor (CF) for predicting OC from organic matter (OM) in
soil and different particle-size fractions in several Mollisols of the
Argentinean Pampas. Several agricultural fields (140) under no-tillage were
sampled before crop sowing at 0–20 cm. SOM was physically separated by wet
sieving, obtaining a coarse particle-size fraction (CPF, 105-2000 μm) and a
medium particle-size fraction (MPF, 53–105 μm). Organic C and OM were
determined by dry combustion (DC) and by LOI in whole soil (WS) and in both
particle-size fractions. The values of OC (0.7–3.6 g 100 g−1) and OM (1.9–7.9 g
100 g−1) varied greatly between the soils. High and significant relationships
(P < 0.001) were found between the different soil fractions determined by DC
and LOI, with OM (105–2000 μm):OC (105–2000 μm) (R2= 0.94) > OM(WS):OC(WS)
(R2 = 0.88) > OM(53–105 μm):OC(53–105 μm) (R2 = 0.82). These results indicated
that the C content in each fraction was in the order of 45%, 50% and 41% for
WS, CPF and MPF, respectively. The LOI method can predict OC in CPF (105–2000
μm) with reliable accuracy. The CF for predicting OC from OM was variable for
each soil fraction considered: 2.23 for WS, 2.00 for CPF and 2.44 for MPF.
Martínez
J.M., J.A. Galantini, M.E. Duval, F.M. López, J.O. Iglesias. 2018.
Estimating soil organic carbon in Mollisols and its particle-size fractions by
loss-on-ignition in the semiarid and semihumid Argentinean Pampas. Geoderma
Regional 12: 49-55.
DOI: 10.1016/j.geodrs.2017.12.004
Download ResearchGate Journal Google
Drive (in ENGLISH)
Nitrogen mineralization indicators under semi-arid and semi-humid conditions: influence on wheat yield and nitrogen uptake
The objectives were i) to assess indicators for
potential nitrogen (N) mineralization and ii) to analyze their relationships
for predicting winter wheat (Triticum aestivum L.) growth parameters (yield and
N uptake, Nup) in Mollisols of the semi-arid and semi-humid region of the
Argentine Pampas. Thirty-six farmer fields were sampled at 0–20 cm. Several N
mineralization indicators, wheat grain yield and Nup at physiological maturity
stage were assessed. A principal component (PC) analysis was performed using
correlated factors to grain yield and Nup. The cluster analysis showed two main
groups: high fertility and low fertility soils. In high fertility soils,
combining PCs in multiple regression models enhanced the wheat yield and Nup
prediction significantly with a high R2 (adj R2 = 0.71–0.83). The main factors
that explained the wheat parameters were associated with water availability and
N mineralization indicator, but they differ according to soil fertility
Martínez
J.M., J.A. Galantini, M.E. Duval, M.R. Landriscini, R.J. García, F. López. 2018.
Nitrogen mineralization indicators under semi-arid and semi-humid conditions:
influence on wheat yield and nitrogen uptake, Communications in Soil Science
and Plant Analysis 49(15) 1907-1921.
doi: 10.1080/00103624.2018.1485931
Download ResearchGate Journal Google
Drive (in ENGLISH)
Edaphic
forms of phosphorus in no-tillage cropping sequences in the Argentine southern
central Pampas
Agriculture significantly affects phosphorus (P)
availability, thereby modifying P equilibrium. The objective of this study was
to evaluate the effect of different crop sequences on the dynamics of soil P
forms under no tillage. Soil samples were collected from a system of five
sequences initiated in 1998. The agricultural sequences followed the scheme
crop diversity (CD), crop-pasture (CP, without grasses), traditional crops 1
(TC1, for limited soils), traditional crops 2 (TC2), and traditional crops 3.
TC3). The available P (Pe) was determined and soil P was fractionated. Organic
P extracted with NaOH (PoNa) was analyzed by spectrometry UV–visible and IR.
Under CP, the available P decreased in both organic and inorganic labile forms,
whereas PoNa values increased. Higher Pe was observed in TC1and TC3. The E4/E6
rates showed that the systems with the lowest degree of aromaticity were CP,
TC1 and TC3. These three management sequences presented high PoNa values and,
from these values, CP showed lower values for Pe, indicating differences in the
chemical quality of the molecule. The 1050/1260 spectra, which relates an
aliphatic ester to an aromatic ester, indicated that the CP and TC3 ratios were
1.3 and 0.94, respectively. In other words, the predominant type of ester in CP
is aliphatic and in TC3 predominant esters would be of the aromatic type. Crop
rotations can produce changes in organic P forms, which will modify the
predominant functional group and the way this nutrient interacts with the soil
matrix. Inclusion of pastures in a rotation maintains plant-available P at
lower levels. However, this is the sequence that keeps moderately labile P
(PoNa) at higher levels
Suñer L., R. García, J.A.
Galantini, H. Forján, A. Paz González. 2018. Edaphic forms of
phosphorus in no-tillage cropping sequences in the Argentine southern central
Pampas. Geoderma 323: 107-115. DOI: 10.1016/j.geoderma.2018.02.027
2017 - - - - - - - - - - - - - - - - - - - - - - -
- - - -
Morpho-structural evaluation of various soils subjected to different use intensity under no-tillage
According to many evidences, in Argentina, no-tillage (NT) coupled with
soybean monoculture leads to adverse soil structure features. While some
farmers have simplified the production system through soybean monoculture
others have intensified the land-use by increasing the number and diversity in
the crop sequence. The effects of this intensification, in terms of soil
structural quality, are contradictory, possibly caused by the increase of
machinery traffic. In order to assess soil structural quality and the
performance of selected morpho-structural variables with different levels of
intensification, we analyzed plots under NT with high and low crop sequence
intensification (Good −GAP- and Poor −PAP-, agricultural practices respectively)
and reference plots in four soils (two Argiudolls, an Haplustoll and an
Hapludert) of the Argentinian Pampean region. The morpho-structural variables
assessed were Visual Evaluation of Soil Structure at field scale (VESS),
visible porosity (Vp), roundness (Rd), eccentricity (Ecc) and 3-D aggregate
features (faces, corners and edges). Plots with higher frequency of cereals in
the sequence (GAP) presented on average higher VESS scores, higher Vp values
and less rounded aggregates with more faces and corners, suggesting that crop
sequence intensification induces favorable structural features. VESS, Vp,
number of faces and corners were strongly correlated with aggregate stability
tests mainly with the fast and fast10s test (r: −0.56, −0.74; 0.48, 0.52; 0.46,
0.49 and 0.42, 0.50, respectively) and with the more labile organic carbon
fractions −POCc and POCf- (r: −0.49, −0.5; 0.5, ns; 0.38, 0.48 and 0.31, 0.43,
respectively). These observations suggest that the variables examined,
concerning aggregates and pores were sensitive to changes in crop sequence and
are useful soil quality indicators. However, the occurrence of platy structures
also under GAP shows the need to adjust the VESS method to the NT system.
Besides, the effect of agricultural intensification on soil morphology was modulated
by soil type. In consequence, this last factor has also to be considered for
the definition of a quality indicator to track the effect of crop sequences
intensification under no-till management.
Behrends K.F.,
M.A. Soria, M.G. Castiglioni, M. Duval, J. Galantini, H. Morrás. 2017. Morpho-structural
evaluation of various soils subjected to different use intensity under
no-tillage. Soil & Tillage Research 169: 124-137.
Production and quality of cover crops in soybean monoculture
Cover crops (CC) are an alternative to improve soil organic matter,
capture labile nutrients and minimizing its leaching losses during long-term
fallows, typical of agricultural systems with high frequency soybean (Glycine
max L. Merr.). The objective was to evaluate the production and nutrient
content of different CC in simplified system (soybean monoculture) under
no-tillage. CC used were: (T) bread wheat (Triticum
aestivum L.), (A) oat (Avena sativa
L.), (V) vetch (Vicia sativa L.) and
(A+V) oat + vetch. Upon drying the CC was determined: production of total
aerial dry matter (MS), biochemical composition (cellulose, hemicellulose and
lignin), macro- and micronutrients. Dry matter production in T and A ranged
between 7.2 and 11.1 Mg ha-1, differing significantly from V with
values between 4.1 and 4.6 Mg ha-1. Carbon concentration did not
differ between CC (43-45% C). The amount of N accumulated in aboveground
biomass ranged between 102 and 212 kg N ha-1, showing differences
only between years. The concentration of structural polymers clearly differ
between CC species, where T and A showed higher concentrations of cellulose and
hemicellulose regarding V. Conversely, V showed higher concentrations of
nonstructural carbohydrates and lignin than grasses. Winter grasses as CC were
more efficient in producing MS and therefore more effectives to contribute to
increased soil organic matter, promoting the recycling of macro- and
micronutrients, preventing the leaching of those most labile.
Wheat-vetch, Biochemical composition
Duval, Matías
E.; Galantini, Juan A.; Capurro, Julia E.; Beltrán, Marcelo J. 2017. Producción
y calidad de diferentes cultivos de cobertura en monocultivo de soja. Ciencias Agronómicas (FCA-UNR) XXIX 7-13.
Aggregate stability of an Argiustol under different tillage systems in the Southwest of Buenos Aires
Land
mismanagement leads to degradation of soil structure, affecting the ecosystem
and jeopardizing the productive potential of soils. Tillage systems modify
carbon content and distribution, and hence influence the structural stability
of soils. This study discusses the effect of no tillage (NT) and conventional
tillage (CT) on aggregate-size distribution and carbon content in comparison
with an uncultivated or natural soil (Nat).The soil samples were taken to the
0-5 and 5-10 cm depths. They were analyzed for total organic carbon, coarse
particulate organic carbon, fine particulate organic carbon and
mineralassociated organic carbon. The content of total carbohydrates and
soluble carbohydrates was determined. The aggregates were isolated by dry- and
wet-sieving and their stability was calculated. All organic carbon forms within
the 0-5 cm depth decreased as soil disturbance was higher, whereas no
differences were observed in the 5-10 cm depth between NT and CT. The fraction
of the dry-sieved aggregates smaller than 1 mm in the 0-5 cm depth turned out
to be the most sensitive to tillage; it increased in the order Nat (17.3%)<
NT (24.9%)< CT (34.6%), following the same tendency as aggregate stability.
Tillage reduction tended to increase the amount of aggregates larger than 2.8
mm, with values of 66 (Nat), 57 (NT) and 37% (CT). Soluble carbohydrate content
in the various sizes of the aggregates isolated by dry-sieving followed the
same tendency as aggregate stability in aggregates larger than 2.8 mm and
smaller than 1 mm. Aggregate stability was associated with the
management-sensitive fraction smaller than 1 mm.
Aggregates, Organic carbon, Organic fractions, Soil
cementing agents
Iglesias J.O.,
J.A. Galantini, A. Vallejos. 2017. Estabilidad de agregados de un Argiustol del
SO Bonaerense con diferentes sistemas de labranza. Ciencia del
Suelo 35(2)
189-204
Rapid characterisation of
agro-industrial effluents for environmental fate by UV–visible and infrared
spectroscopy from fractions obtained by centrifugation
Agro-industrial systems (e.g. dairy farms, feed lot, pig breeding and
food processing plants) provide large quantity of organic wastes that could be
recycled within the productive systems. However, the basic chemical
characterisation is not enough to predict the effect that they may generate on
the environment. In this study, a centrifugation process was applied at various
speeds between 3000 and 15,000 rpm and carried out separately on two different
livestock effluents (dairy farm and pig anaerobic digestate), in order to
obtain supernatants and precipitates, which were studied separately. The more
water soluble fractions, with lighter components and/or simpler structures,
remained as liquid supernatants, while the more complex fractions, with higher
molecular weight and/or water insoluble fractions, constituted the solid
precipitates. An increase in the centrifugation rate did not produce the
differential precipitation of dissimilar functional groups. Hence, 5000 rpm was
the most adequate velocity since it generated clear supernatants without
denaturation of the organic matter. A basic cost-effective chemical analysis,
complemented with ultraviolet-visible and Fourier transform infrared
spectroscopy, enables a set of properties to be established qualitatively and
quickly for the multiple components of the organic matter for its later use as
fertilisers or amendments. This rapid and economical technique allows for a
characterisation prior to the reuse of the effluents, which is necessary to
optimise their application and avoid environmental problems.
Iocoli G.A., O.I.
Pieroni, M.A. Gómez, M.B. Alvarez & J.A. Galantini. 2017. Rapid characterisation
of agro-industrial effluents for environmental fate by UV–visible and infrared
spectroscopy from fractions obtained by centrifugation. International Journal of Environmental Analytical Chemistry 1-12
pags. DOI: 10.1080/03067319.2017.1354993
A rapid chemical method for estimating potentially mineralizable and particulate organic nitrogen in Mollisols
The objective of this study was to obtain an indicator of labile
nitrogen (N) through a cost- and time-saving procedure by evaluating the
relationships among potentially mineralizable N (N0), particulate
organic matter N (POM-N) and soil organic N extracted through partial soil
digestion with different concentrations of sulfuric acid (H2SO4).
Soil sampling (0–20 cm) was from nine fields under no-tillage. The N0
and POM-N were determined by long-term aerobic incubation and soil physical
fractionation, respectively. A simple chemical method was developed by soil
digestion at 100°C for 4 h with different concentrations of H2SO4
(0.1, 0.5, 1, 6, 12, and 24 mol L−1). All acid concentrations showed
significant relationships with N0 as POM-N; however, the best
prediction was resulted for 0.5 mol L−1 (R2 = 0.90–0.94,
respectively), thus using this methodology as soil labile N indicator. This
method would optimize N0 and POM-N estimation in short term and at a
low cost.
Palabras clave
Martínez J.M.,
J.A. Galantini. 2017. A rapid chemical method
for estimating potentially mineralizable and particulate organic nitrogen in
Mollisols. Communications in Soil
Science and Plant Analysis 48(1) 113-123.
Tillage effects on labile pools of soil organic nitrogen in a semi-humid climate of Argentina: A long-term field study
Tillage systems strongly affect nitrogen (N) mineralization. However,
there is still only limited information on the relationship between N in labile
soil organic matter (SOM) fractions and crop N uptake under different tillage
systems in areas with poor water availability. This study discusses the
long-term effect of two tillage systems on i) the N-content in labile organic
matter fractions and their relationship with the N mineralization potential at
three depths (0-5; 0-10 and 0-20 cm), ii) the factors that affect the N
mineralization potential, and iii) the relationship between potentially
mineralizable N (N0) and crop N uptake in a semi-humid climate. In a long-term
experiment, a Typic Argiudoll was sampled under two contrasting tillage
systems: no-tillage (NT) and conventional tillage (CT). The soil sampling was
performed over four years of the crop sequence (2003, 2009, 2010 and 2011) when
the plots were sown with winter wheat (Triticum aestivum L.). They were
analyzed for N0 in the form of anaerobic N, soil organic nitrogen (SON),
physically separated SOM fractions and crop N uptake. Higher values of SON and
labile soil N fractions were observed under NT at all three depths. Significant
differences in N0 were found between the tillage systems, with greater values
under NT. Significant (P <0.05) and positive correlations between N0 and
fine particulate organic carbon (fPOM-C) (r≥0.66) were found in CT and in NT at
the three depths, whereas highly significant (P <0.001) and negative
relationships between N0 and fine particulate organic N (fPOM-N) (r≥-0.83) were
found under both tillage systems at 0-5 and 0-10 cm. The most pronounced
difference in these relationships between tillage systems was observed at the
0-5 cm soil depth. Significant correlations of N0 with residue input from
previous crops and the fallow period were observed under both tillage systems
and for all three depths. Regarding the relationships between N0 and wheat N
uptake, no significant correlations were found for any tillage system or depth.
Soil organic N fractions were shown to be strongly influenced by the residue
input from the previous crop and by variable weather conditions during the
fallow period. The higher content of SON fractions under NT was associated with
a higher N mineralization potential, however, it did not result in increased N
availability and N uptake by wheat, because of climatic conditions during the
crop growing season.
Palabras clave
Martínez J.M.,
J.A. Galantini., M. Duval. 2017. Tillage effects on labile pools of soil organic nitrogen in a
semi-humid climate of Argentina: A long-term field study. Soil
& Tillage Research
169:71-80
Adjustments in organic carbon
estimation by loss/on/ignition method in Mollisols of the Southwest Buenos
Aires Province
Soil
organic carbon (SOC) quantification is crucial for understanding the cycling in
the terrestrial ecosystems. It is important to use methodologies of easily implementation
that determine the SOC properly. The aims of this study were to determine: i)
the optimal temperature and time to maximize the prediction of SOC and ii) a
suitable conversion factor (fc) to estimate the SOC by loss-on-ignition method
(MC) in Mollisols of the southwest Buenos Aires Province (SOB). During 2010 and
2011, seventy plots under no-tillage located in the SOB, Argentina, were
sampled at 0-20 cm depth. Soil organic carbon values determined by dry
combustión (CS) in an elemental analyzer were considered as reference values.
Soil organic matter (OM) values were determined by MC in a muffle furnace at
different temperatures (360, 430, 550 and 600 °C) and times (during 2 and 4
hours). No significant interactions were detected between both factors.
Significant effect of different temperatures (p<0.001), while, no
significant effect of calcination time
(p=0.66) were detected. Linear regressions between SOC and OM at different
temperatures showed significant relationships (p <0.001) with high
coefficients of determination (R2 =0.91-0.95). The best
prediction of SOC was found with 550°C temperature (R2= 0.95). The fc was 2.2, which would
indicate that in these soils the C content in OM was 45%. These results suggest
that MC with an adequate fc, is an easily implementable protocol that provides
estimation of SOC comparable with the reference CS method.
Soil organic matter, dry combustion, conversion factor.
Martínez Juan
Manuel, Matías E. Duval, Fernando M. López, Julio O. Iglesias, Juan A.
Galantini. 2017. Ajustes en la estimación de carbono orgánico por el método de
calcinación en molisoles del sudoeste bonaerense. Ciencia del
Suelo 35(1)
181-187.
Download
ResearchGate Journal Web Google Drive (in SPANISH)
Links
https://drive.google.com/open?id=1o3oaXtsLU4809cp399Nn4UIFFHeWCtAd
Use of a three-compartment model to evaluate the dynamics of cover crop residues
Cover crop (CC) residues protect the soil from erosion and their
permanence on the surface is largely influenced by their biochemical
constituents. In this study the dynamics of CC residue decomposition by
applying mathematical models was described. The kinetics of decomposition of
residues was obtained from a laboratory incubation experiment. Three CC shoot
residues were applied on the soil surface and incubated for 362-days (with
eight sampling times). Oats and vetch residues decomposed the most than clover,
which k values were 3.6 × 10⁻³, 3.7 × 10⁻³ and 5.3 × 10⁻³ day⁻¹, respectively.
The three-compartment model (non-structural carbohydrates,
cellulose-hemicellulose and lignin) to simulate residue decomposition,
presented a close fit between simulated and measured data. The decomposition
rate constant (k) of CC can be used to estimate how long residues will remain
in the field and how they could affect soil organic carbon.
Palabras clave
Sa Pereira E, J.A. Galantini, M. Duval. 2017. Use of a
three-compartment model to evaluate the dynamics of cover crop residues. Archives of Agronomy and Soil Science 63(11)1623-1629.
http://dx.doi.org/10.1080/03650340.2017.1296137
Decomposition from legume and non-legume crop residues: effects on soil organic carbon fractions under controlled conditions
Cover crop (CC) residues protect the soil from erosion and their
permanence on the surface is largely influenced by their biochemical
constituents. We performed a study under controlled conditions to investigate
the dynamics of legume and non-legume CC residues decomposition and the
transformations of the soil labile organic carbon fractions in the surface
layer (0-15 cm). The experiment was carried out on a Typic Argiudoll (clay
loam, 27.4 g kg⁻¹ soil organic
matter, 14 mg kg⁻¹ extractable
phosphorus and 6.5 pH) placed in undisturbed pots (1570 cm³) in a greenhouse
under controlled conditions of temperature (25 ± 1 °C). We evaluated three CC
species (oat, Avena sativa L.; vetch,
Vicia sativa L.; Persian clover, Trifolium resupinatum L.) and a no-CC
control (fallow). Shoot residues were applied on the soil surface at 5.4, 5.4
and 2.7 g dry matter (equivalent to 6, 6 and 3 Mg ha⁻¹ for oat, vetch
and clover, respectively) and incubated for 362-days (eight sampling times).
The water content in the pots was maintained periodically by weight at 60% of
soil water-holding capacity. The soil samples were analyzed for particulate
organic carbon (POC), and total and soluble carbohydrates (CHt and CHs, respectively).
Oat and vetch residues decomposed faster than clover, with the decomposition
rate constant (k) values of 1.3, 1.4 and 1.9 year⁻¹, respectively. At the end of the
experiment, POC concentration was lower in vetch (1.83 g kg⁻¹) and clover
(1.96 g kg⁻¹) than in oat
(2.21 g kg⁻¹) and fallow
(3.00 g kg⁻¹), indicating a
loss of 45-64% from their initial values. Soil CHt was influenced by residue
quality, where the periods of greatest residue decay (vetch 21-59 days and oat
93-130 days) corresponded to higher soil CHt. Hence, this organic carbon
fraction is sensitive to residue decomposition and can be indicators of changes
in soil organic matter over short periods of time.
Palabras clave
Sa Pereira E,
M. Duval, J.A. Galantini. 2017. Decomposition from legume and non-legume crop residues: effects on
soil organic carbon fractions under controlled conditions. Spanish Journal of Soil Science 7(2) 86-96 https://doi.org/10.3232/SJSS.2017.V7.N2.06
Quality of cover crops in Southwest
Bonaerense under no tillage systems
No-tillage
system with fall/winter cover crop (CC) ensures that large amounts of different
types of organic residue are supplied to the soil. The biochemical composition
of each residue, especially its C:N ratio and lignin, plays an important role
in nitrogen (N) and carbon (C) soil dynamics, as well as the availability of
nutrients for the next crop. The objective of this study was to evaluate the
quality parameters of CC based on the quantity and quality of the residue
contributed. The experiments were carried out on Argiudioles typical of the
Coronel Suárez (Pcia. de Bs. As.) Species used as cover crops were: Oats (Avena
sativa L.), Hairy vetch (Vicia sativa L. Thell.), Clover persia ‘‘grazing’’
(Trifolium resupinatum L var. ‘‘Lightning’’), Clover Persia ‘‘coverage’’
(Trifolium resupinatum L. var. ‘‘Laser’’). The determinations were: a)
Production of forage (Mg MS ha-1), b) N, c) neutral detergent fiber
(NDF) and acid (FDA), nonstructural carbohydrates (CNES), carbon (C%) and
Lignin. The aerial biomass of Hairy vetch presented the highest concentrations
of N in the dry matter (MS) produced. When the oats were fertilized they were
able to increase the contributions of N to the soil present in the aerial
biomass of the residue to 50%. The aerial biomass of Hairy vetch presented the
highest yields and concentrations of lignin. The different CC presented C:N and
LIG:N ratios that were based on the amount of MS produced by the aerial biomass
of the crop and its phonological state at the time of drying. The temperature
and the moment of evaluation modified quantity and quality of the residues. The
parameters evaluated were sensitive to these changes.
Coverage crops, cellulose, hemicellulose, lignin.
Sá Pereira E.,
J.A. Galantini, A. Quiroga. 2017. Calidad de cultivos de cobertura en sistemas
de siembra directa del sudoeste bonaerense. Ciencia del
Suelo 35(2)
337-350
Changes in soil pH and phosphorus availability during decomposition of cover crop residues
The aim of this study was to determine the effect of winter cover crops
(CC) residues on soil pH and phosphorus (P) availability. Three incubation
assays were performed in pots using two CC: vetch (V) (Vicia villosa Roth.) and oats (Oa) (Avena sativa L.). Soil samples
were taken from ten sites at 0-20 cm depth. The rate of residues were 0 (D0),
10 (D1), 20 (D2), 30 (D3) and 40 (D4) g dry matter kg-1 soil and the soil
sampling was after 10, 20, 30, 60, 90 and 120 days of incubation. Soil pH,
extractable P (Pe), and soil organic matter (SOM) and its fractions were
determined. The pH increase was correlated with the rate applied (D1< D2<
D3< D4). No differences were found for pH comparing V and Oa residues with
low residue rates. Soil pH changes were dependent from initial pH and SOM
fractions in different soils across the incubation period. The multiple
regression models showed that the pH changes were dependent on initial pH level
and SOM fractions with a high R2 (0.81). Cover crops residues and its
quantities produced different changes on pH - especially at the beginning of
the incubation- which influenced the P availability.
Vanzolini J.I.,
J.A. Galantini, J.M. Martínez, L. Suñer. 2017. Changes in soil pH and phosphorus availability
during decomposition of cover crop residues. Archives of Agronomy and Soil Science 63 (13) 1864-1874. http://dx.doi.org/10.1080/03650340.2017.1308493
2016
- - - - - - - - - - - - -- - - - - - - -
- - - - - - -
Soil
organic matter quality, macro and micronutrient availability in response to the
inclusion of wheat as cover crop
Cover crops appear as an option to improve the balance
of carbon (C) and its quality. The aim of this study was to study the effect of
wheat as a cover crop on the dynamics of organic matter and the availability of
some macro and micro nutrients under different crop rotations. This work was
carried out in a long-term experiment under non-tillage system. Treatments
were: soybean-soybean (S-S), soybean-cover crop-soybean (S-CC-S),
corn-soybean-wheat/soybean (C-S-W/S) and corncover crop-soybean-wheat/soybean
(C-CC-S-W/S). As principal results, it was observed that the fraction of
organic carbón between 53 and 105 mm (COPf) was significantly increased when CC
were added to soybean monoculture. The carbón fraction of less than 53 mm
(COa), was higher when cover crop were incorporated to the rotations. Soybean
monoculture had a value of total organic carbon (COPg + COPf) of 11.1 g kg-1,
being the lowest value of all treatments and significantly lower than S-CC-S
(17 g kg-1). Soil macronutrients concentration had no differences
between treatments. Rotations with grasses and legumes (M-S-T/S) determined in
general a greater accumulation of zinc (Zn) and manganese (Mn) (2.2 and 63 mg
kg-1 respectively) than soybean monoculture (1.4 and 50 mg kg-1)
in the depth of 0-5 cm. The concentration of these micronutrients was
positively correlated with organic matter content. In this year of study, the
CC did not seem to have affected the concentration of micronutrients, thus
successive analysis should be performed in order to study the effect of CC in
micronutrients dynamics in time.
Organic fractions, nutrient availability,
crop rotations
Beltrán M., L.
Brutti, R. Romaniuk, S. Bacigaluppo, F. Salvagiotti, H. Sainz-Rosa, J.A.
Galantini. 2016. Efecto del trigo como cultivo de cobertura sobre la dinámica
de la materia orgánica en el suelo y la disponibilidad de macro y
micronutrientes. Ciencia del Suelo 34(1) 67-79.
Comparison between
agricultural and natural quality indices based on organic carbon
Literature exhibit a great number of soil quality
indices, many of them based on organic carbon and its fractions, for a wide variety
of natural and cultivated soils. In four sites located in the argentine Pampa
region, the effect of the sequence and intensity of crop rotations on different
organic carbon fractions in no-tilled soils, and the sensitivity of some
quality índices to management practices were evaluated. At each site, three treatments
were identified: two different agricultural scenarios in terms of crop
rotation, fertilizers and use of agrochemicals (diversified intensive and
regional representative managements, MID and MRR, respectively) and an
undisturbed environment, natural (ASD) adjacent to agricultural sites as
control treatment. Agricultural management with a high frequency or soybean
monoculture caused COT decreases of about 30% in 0-10 cm depth. These decreases
mainly affected labile fractions (particulate CO 105-2000 μm and particulate CO 53-105 μm) which decreased by 50% and 40%
with respect an ASD field. These situations present the worst values in the
most indices including labile fractions. However, the magnitude of the observed
changes in these indices were lower in relation to those associated with the
COT. The COT stratification index (0-5:5-20 cm) showed differences between
treatments, which ranged from 2.0 (ASD) to 1.5 (MRR). The differential carbon
input to the soil between treatments was reflected in the carbon pool index (IRC),
considering a simple index to measure and sensitive to detect differences
between agricultural managements. The results highlight the importance of the
COT as universal indicator and the need to take into account local issues
either management and/or seasonal, for the interpretation of the indices
associated with the most labile fractions.
Stratification index; soybean frequency; labile fractions.
Duval M.E.;
J.A. Galantini; J.M. Martínez; J.O. Iglesias. 2016. Comparación de índices de
calidad de suelos agrícolas y naturales basados en el carbono orgánico. Ciencia
del Suelo 34(2) 197-209.
Sensitivity of different
soil quality indicators to assess sustainable land management: Influence of
site features and seasonality
The turnover rate of labile organic fractions varies
continuously due to different soil uses and managements, weather conditions and
sampling time. The aim of this study was to quantify the effect of different
agricultural management, season and soil type on soil organic carbon (SOC) and
its different fractions. The study was conducted on four sites located in the
Argentinean Pampas. In each site, three treatments were defined: Good
Agricultural Practices (GAP), Poor Agricultural Practices (PAP) and Natural
Environment (NE). During two consecutive years (2010 and 2011) and at two
different times (February and September) undisturbed soil samples were taken at
0–20 cm depth. Variables assessed included: SOC and its organic fractions:
coarse (POCc) and fine (POCf) particulate organic carbon, SOC associated with a
mineral fraction (MOC), total (CHt) and soluble (CHs) carbohydrates, bulk
density (BD), and large pores (P>30). Also, indices associated with soil and
management variables were determined. SOC reductions caused by agricultural
practices were mainly from POCc. This fraction represented 34–52% and 50–74%
for PAP and GAP, respectively, of the observed in NE. The carbon pool index
(CPI) shows that agricultural treatments induced greater variations in all the
labile organic fractions compared with SOC and MOC. In turn, the magnitude of
variability was different among fractions, where temporal fluctuations
increased according to the following order MOC < SOC < POCf < CHt < CHs < POCc. Independently of the
soil type, the CPI was a sensitive indicator of soil quality in these systems
under no-tillage. The multivariate analysis has proven to be an efficient
analytical methodology for the identification of soil indicators that respond
to agricultural practices, in which chemical properties (POCf and CHt),
physical (BD and P>30), and indices (SOC: clay, structural index and intensification
sequence index) were the variables that best explained the total variance of
information of the four sites. Therefore, these indicators/indices should be
included in any minimum data set for evaluating the agricultural soil quality
under no-tillage in the studied area.
Winter
cover crops in soybean monoculture: Effects on soil organic carbon and its
fractions
The current agricultural production systems in the
Pampas Region have been significantly simplified by cultivating large land
areas under no tillage (NT), where soybean is the predominant crop. These
systems with long periods of fall-winter fallow and poor annual input of carbon
(C) into the soil lead to soil degradation, thereby affecting physical and
chemical properties. A 6-year cover crop study was carried out on a Typic
Argiudoll under NT in the south of Santa Fe, Argentina. Various winter species
were used as cover crops: wheat (W), oat (O), vetch (V), an oat + vetch mixture
(O + V) and a control (Ct) treatment without a cover crop. We examined the
influence of cover crops on the following soil organic C-fractions: coarse
particulate organic carbon (POCc), fine particulate organic carbon (POCf) and
mineral-associated organic carbon (MOC) from 2008 to 2011. Aboveground carbon
input by the cover crops was related to the June to October rainfalls. In
general, the W and O treatments supplied a higher amount of C to the soil;
these gramineous species produced 22 and 86% more biomass than O + V and V. The
water cost of including cover crops ranged from 13 to 93 mm compared with Ct.
However, this water-use did not affect soybean yields. On average, gramineous
species (pure stand or mixture) supplied more than 3.0 Mg C ha-1
year-1 to the soil, whereas V supplied less than 2.0 Mg C ha-1
year-1. Increase in the mean annual C-input by residues into the
soil (cover crop + soybean) explained most SOC variation (R2 = 0.61;
p < 0.05). This relationship was more evident with labile soil organic
fractions, both for POCc (R2 = 0.91; p < 0.001) and POCc + POCf
(R2 = 0.81; p < 0.001). The stratification ratios of SOC (SI, 0-5:
10-20 cm) reflected differences among treatments, where >2.0 for W; 1.7 for
O, O + V and V, and <1.5 for Ct. Soil physical fractionation by particle
size showed that cover crops affected the most dynamic fraction directly
associated with residue input (POCc) at 0-5 and 5-10 cm. At 0-5 cm, the effects
were observed in the most transformed fractions (MOC and POCf) 4 years after
the experiment started, whereas at 0-20 cm, differences in the labile fractions
(POCc and POCf) were found at the end of the experiment (6 years). Although
C-input by the cover crops fueled decomposition of labile soil organic
fractions, concentration of surface SOC and its associated fractions (POCc,
POCf and MOC) was modified after 6 years. This effect became noticeable during
the third year when the plots under cover crops showed a higher SI than the
traditional fallow.
Organic fractions, Carbon balance,
carbon stratification index
Duval M.,
J.A. Galantini, Julia E. Capurro, J.M. Martinez, F.M. López. 2016.
Winter cover crops in soybean monoculture: effects on soil organic carbon and
its fractions. Soil & Tillage Research 161:95-105
doi:10.1016/j.still.2016.04.006
Quality
and Quantity of Organic Fractions as Affected by Soil Depth in an Argiudoll
under Till and No-till Systems
Aims: The
aim of this study was to evaluate the long-term effect of tillage systems on
the quantity and quality of organic carbon fractions at different soil layers.
Study Design: The
experimental design was a split plot with three blocks. The long-term effects
(25 years) of conventional- (CT) and no-tillage (NT) systems on a Tipic
Argiudoll was sampled at 0-5, 5-10, 10-15 and 15-20 cm soil depth.
Place and Duration
of Study: The field experiment was carried out at Tornquist
(38° 07’ 06” S - 62°02’ 17” O) and soil sampling was performed during wheat
seeding (June 2011).
Methodology: Total
soil organic carbon (SOC) content and the following fractions were determined:
Coarse particulate (POCc, 105-2000 µm), fine particulate (POCf, 53-105 µm) and
mineral-associated (MOC, 0-53 µm) carbon fractions; humic (HA) and fulvic (FA)
acids; and total (CHt) and soluble (CHs) carbohydrates. The main
physico-chemical properties of HA and FA were analyzed using both FT-IR and
fluorescence spectroscopies.
Results: After
25 years, total SOC at the 0-20 cm depth was 9% higher in no-tilled than in
tilled soils. The POCf was the SOM fraction that turned out to be the most
sensitive to tillage effects. The POCc:POCf:MOC ratio at 0-20 cm was
similar for NT (3:14:82) and CT (5:10:84); however, differences were found
across soil depths. Tilled soils showed higher aromaticity, starting by
CH-degradation, in more superficial soil layers.
Conclusion: The
no-tillage system presented a different pattern which can be related to distribution
of crop residues and conditions for humification along the soil depth.
Tillage system; soil organic carbon;
chemical and physical fractionation.
Galantini,
J.A.; M. Duval; J.M. Martinez; V. Mora; R. Baigorri & J.M. García-Mina. 2016.
Quality and quantity of organic fractions as affected by soil depth in an
argiudoll under till and no-till systems. International Journal of Plant &
Soil Science 10 (5) - doi:10.9734/IJPSS/2016/25205
Nitrogen
recovery efficiency by the difference and isotopic dilution methods
The nitrogen (N) use efficiency can be determined by
the isotopic dilution or by the difference method. The objectives were to
measure the destination of foliar fertilizer and to compare the Nitrogen
Recovery Efficiencies (NRE) between the mentioned methods. A field experiment
was conducted in the southwest of the Buenos Aires Province (Las Oscuras).
Nitrogen rates of 0, and 50 kg N ha-1 were applied at sowing and 0
and 25 kg N ha-1 at anthesis. The enriched urea was applied in
anthesis and post-anthesis in the microplots. Yields were low with no response
to the initial or foliar fertilization: 2100 and 2154 kg ha-1 for 0
and 50N without foliar N and 2160 and 2303 kg ha-1 with foliar N
application. In the isotopic plots, wheat accumulated 83 kg in aboveground
biomass and 52 kg N ha-1 in grain without a significant impact of
initial or foliar fertilization. Nitrogen from the foliar fertilizer was accumulated
20% in aerial dry matter (ADM) and 12% in the grain, with a recovery of 6 kg N
ha-1. Accumulated N in straw ranged 10 kg N ha-1 and
unrecovered N varied from 7.2 to 8.3 kg N ha-1 (30%). The NRE varied
from 30% to 54 according to the difference method for the initial 0 and 50N
treatments in ADM and grain, with an accumulation of 2.4 to 6 kg N ha-1.
Isotopic determined NRE was of 70% in ADM and 25 % in grain. Again, grain
accumulation was of 6 kg N ha-1. The differences between the methods
suggested the need to identify the factors that influence these estimates.
Wheat, 15N, Nitrogen
recovery, Foliar urea.
Landriscini
M.R., J.A. Galantini, J.M. Martínez. 2016. Destino y recuperación del
fertilizante foliar en trigo usando la técnica isotópica de 15N. Ciencia
del Suelo 34(1) 155-162.
Nitrogen
fertilization in wheat in the Subhumid Region: nitrogen and water use
efficiencies
Water and nitrogen (N) are typically the main wheat
crop production factors in regions with water constraints. For this reason, it
is of great importance to increase the N use efficiency (EUN) -when applying
fertilizers- and the water use efficiency (EUA) in sub-humid environments. The
objectives of this study were i) to analyze wheat response to different N
rates, ii) to evaluate the EUN and EUA of total aboveground biomass (MST) and
grain yield, and iii) to predict these efficiencies with models using principal
components (CP) related to MST and grain yield as variables for five years in a
sub-humid environment. During the 2008-2012 years, nitrogen fertilization
trials were conducted in wheat using four rates (0-25-50-100 kg ha-1)
applied at sowing. At physiological maturity, MST and grain yield were
measured, and EUN and EUA were calculated for both parameters. The CP analysis
was performed using available N and soil moisture at planting, and rainfall in
function of MST and grain yield. Three CP were made for each parameter, with a
full explanation of 90% and 96% of the MST and grain yield total variance. The
NUE predictions used three CP with a high fit (R2 = 0.78 - 0.81) for
MST and grain yield. However, the EUA predictions of MST and yield were low (R2
= 0.38 to 0.45), excluding from the model the CP highly influenced by the
available N. The high variability in water availability did not allow a
significant increase in the EUA by N application, showing that water is the
most limiting factor in this environment. The use of CP as regressor variables
allowed accurate models for EUN prediction of MST and grain yield.
Triticum aestivum L.; Erratic rainfalls;
Principal components.
Martínez
J.M., J.A. Galantini, M.R. Landriscini, F.M. López, M.E. Duval. 2016. Fertilización
nitrogenada en la región subhúmeda Bonaerense: Eficiencia del uso del agua y
del nitrógeno. Ciencia del Suelo 34(1) 81-92.
Diagnosis of nitrogen
fertilization using a chlorophyll meter in wheat under rainfed conditions in
the southwest of Buenos Aires province under two different previous crops
The chlorophyll meter could be used to improve the
diagnosis of nitrogen (N) deficiency. The objectives of this study were to: i)
evaluate wheat (Triticumaestivum L.) yield after two previous crops, ii) assess
the effect of the previous crop on the green index (IV) by chlorophyll meter
readings, and iii) verify the usefulness of the chlorophyll meter in advanced
growth stages of wheat to predict the effect of foliar N application on wheat
production and quality in the semiarid region of the southwest of Buenos Aires
province. In 2011, a fertilization trial on wheat (cultivar Buck Malevo) was
conducted under no-tillage after two contrasting previous crops: wheat and pea
(Pisum sativum L.). In each case, different N rates (0, 25, 50, and 100 kg N
ha-1) in the form of urea (46-0-0) were applied manually at crop emergence. At anthesis,
chlorophyll meter readings were taken in the last expanded leaf and in one half
of each plot a foliar N fertilizer was applied at a rate of 25 kg N ha-1. At
physiological maturity, total aerial biomass (MST), grain yield, crop N uptake,
and protein content were determined. Pea as a previous crop increased the
production of MST, grain yield and N uptake, but no effect was detected on
protein. Protein content was significantly increased by foliar N fertilizer
application, regardless of previous crop. The chlorophyll meter is a useful
tool that could be used in advanced stages of wheat to fine-tune the diagnosis
of N needs. which would allow improving grain quality in the semiarid
environment studied.
Key words Foliar N application;
previous crop; green index.
Martínez
J.M., M.R. Landriscini, G.V. Minoldo, J.A. Galantini. 2016. Uso de un
clorofilómetro para el diagnóstico de la fertilización nitrogenada en la región
del sudoeste bonaerense en trigo de secano sobre dos antecesores. Ciencias
Agronómicas (FCA-UNR) 28: 35-43.
Soil porosity in Ustolls
under no-till systems in Southwestern Buenos Aires
In agricultural production the appropriate soil
physical quality is essential to achieve good crop yields with minor
environmental effect. Since no tillage (NT) use broadly expanded in
southwestern Buenos Aires, a more detailed knowledge of the physical soil
condition under this system is needed. With the aim of analyzing the present
physical quality, pore size distribution was determined in Ustolls of
southwestern Buenos Aires province under NT (AG) and in quasi pristine
environments (AN). Also, the influence of the different granulometric fractions
on physical properties was evaluated. Analyzed soils showed a poor subsurface
aeration porosity tendency demonstrated by the low macroporosity of the AN
(16.6%). In agricultural soils these limitations increased due to lower
macroporosity (11.8%). Near 88% of AG presented subsurface physical
characteristics that would limit wheat (Triticum aestivum L.) and barley
(Hordeum vulgare L.) development, even after 12 years under NT. The main
limitation was associated with a low macroporosity (pores> 30 μm) that could affect soil aeration
and root growth. Although it is not possible to attribute the macroporosity
loss to NT management, the way it has been implemented in the region has not
been able to reverse the soil physical quality problems. It is necessary to
develop land management practices that contribute to the biotic soil structure
regeneration (e.g. rotations with pastures, inclusion of crops with deep roots)
to ensure adequate physical fertility in subsurface layers of Ustolls under NT
in southwestern Buenos Aires.
Key words. Soil physics; Macropores;
Tillage.
López F.M.;
M.E. Duval, J.M. Martínez, J.A. Galantini. 2016. Porosidad de Ustoles bajo
siembra directa en el Sudoeste Bonaerense. Ciencia del Suelo
34(2) 173-184.
Soil Humic and Fulvic
Acids from Different Land-Use Systems Evaluated By E4/E6 Ratios
Changes in land-use systems such as the introduction
of trees on agricultural land can give rise to changes in the physicochemical
properties of the soils, also affecting the quantity and quality of organic
matter incorporated into the system. The present study assesses humic
substances (HS) in the soil such as humic acid (HA) and fulvic acid (FA) by
looking at the relationship between the optic densities determined at 465 and
665 nm (E4/E6 ratio). Topsoil samples (0–20 cm) from pine woodlands 60 years of
age were compared with agricultural soils of similar age in the central-south
region of the Province of Buenos Aires, Argentina. The pH of the topsoil from
beneath the pine trees was highly acidic (5.0 vs. 6.2) and a significant
increase in the level of organic carbon (OC) was registered. The carbon to
nitrogen (C/N) ratio was also higher (by one order of magnitude) beneath the
pine trees, although the humification conditions of the soil organic matter
(SOM) were good in the soils of both studied land-use systems. The E4/E6 ratio
was higher in the HA and FA 2º (second extraction) beneath the pines,
indicating a smaller molecular size of the HS bound to the clay minerals. This
fact can be attributed to the higher concentration of hydrogen ions beneath the
pines and consequently the loss of polyvalent cations, mainly calcium. The most
labile organic molecules (FA 1º – first extraction) were of a larger size in
soils beneath the pines, most likely owing to a specific characteristic of the
Pinus genus, although the fraction in question constitutes a minority fraction
among the HS. Clear differences were established between the E4/E6 ratios in HA
and FA, making this a highly useful method for determining molecular changes in
HS as a result of changes in land use.
Fulvic acid; humic acid; pinus
afforestation
Zalba P., N.M. Amiotti, J.A. Galantini, S. Pistola. 2016. Soil humic and fulvic acids from different land use systems evaluated by E4/E6 ratios. Communications in Soil Science and Plant Analysis 47 (13-14) 1675-1679. Doi 10.1080/00103624.2016.1206558
2015 - - - - - - - - - - - - -- - - - - - - - - - - -
- - -
1992 - - - - - - - - - - - - -- - - - - - - - - - - - - - -
Effect
of sorghum residues on wheat productivity in semi-arid Argentina. I. Stover
decomposition and N distribution in crop
Humification and residual
effects of 3-month-fallowed sorghum residues on the productivity of winter
wheat in a petrocalcic Haplustoll soil in semi-arid Argentina were studied.
15N-labelled urea was applied at sorghum harvesting-mulching (or beginning of
fallow, F), wheat seeding (S) and tillering (T). Sorghum residues interacted
strongly with N added to the soil. Total aerial plant dry matter (TADM) was
lowest (4.94 Mg ha-1) when N was added at the beginning of fallow
thus indicating a strong N immobilization, and highest (8.30 Mg ha-1)
when N was incorporated at S. The N uptake followed a similar pattern. The
percentage of N derived from fertilizer and that of recovery as well as the N
content of the TADM increased from F to S to T. These data suggest that the
sorghum residues immobilize larger amounts of N when it is applied at the
beginning of fallowing than when it is incorporated at a later time such as
seeding and tillering.
Rosell
R.A., J.A. Galantini, J.O. Iglesias, R. Miranda. 1992. Effect of sorghum
residues on wheat productivity in semi-arid Argentina. I. Stover decomposition
and N distribution in crop. The Science of the Total Environment, 117/118:
253-261.
Download (in ENGLISH) MEGA Google-Drive ResearchGate Journal Scielo
No comments:
Post a Comment