Soil Physical compaction in production systems

Physical properties in no till soils of the southwest of Buenos Aires

Soil physical quality has great importance as a regulator of several processes that affect the functioning of agroecosystems. However, because physical quality problems are complex, persistent, difficult to solve, often its importance is not recognized and its effects are attributed to other causes. Since the large expansion of no tillage (NT) in the southwest of Buenos Aires (SOB), it is needed a more detailed knowledge of the physical condition of soils under NT. In addition, in this chapter there were included some aspects to be considered in the future for the adequate implementation of the NT in the region, which would allow the development of conservation agriculture (CA). Soils under NT in the region showed great variations in the accumulation of surface residues and a large proportion did not have adequate soil cover (> 30%), a necessary requirement of CA. Therefore, in studies that evaluate the effect of NT it is crucial to detail both the amount of residues and the soil cover. In terms of soil porosity, the main limitation was associated with low macroporosity (pores> 30 μm) that would affect soil aeration and root growth. Although it is not possible to attribute the loss of macroporosity to NT management, the way in which it has been implemented in the region (e. g. used in soils with a plow pan, lack of rotations, scarce soil cover) has not been able to reverse the problems of physical degradation. In soils of the SOB under NT it is necessary the development of land management practices that contribute to the biotic regeneration of soil structure (e.g. pasture rotations, inclusion of crops with deep roots) to ensure adequate physical quality. In addition, in the region it would be very important to increase soil cover by residues and to establish crop rotations, to move towards CA.

López, F.M.; M. Duval; J.M. Martínez; J.A. Galantini. 2018. Propiedades físicas en suelos bajo siembra directa del sudoeste bonaerense. En: Compactaciones Naturales y Antrópicas en Suelos Argentinos (Eds. Perla Imbellone y Carina Álvarez) 532-547.

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Cover Crops in the Production System

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 (PCOf) 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.

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Cover Crops in the Production System

BOOK CHAPTERS

Cultivos de cobertura de Vicia villosa Roth. en el valle bonaerense del Río Colorado

Vanzolini J.I.; J.A. Galantini; R. Agamennoni. 2013. Cultivos de cobertura de Vicia villosa Roth. en el valle bonaerense del Río Colorado. Cap 4 en “Contribución de los cultivos de cobertura a la sustentabilidad de los sistemas de producción”, Eds. C. Álvarez; A. Quiroga; D. Santos; M. Bodrero, Ediciones INTA, págs. 21-28. ISBN 978-987-679-177-9

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Sistemas de cultivos de cobertura de suelo de otoño-invierno: Sus efectos sobre la disponibilidad de agua

  

Sá Pereira E. de, J.A. Galantini, A. Quiroga. 2013. Sistemas de cultivos de cobertura de suelo de otoño-invierno: Sus efectos sobre la disponibilidad de agua. Cap 10 en “Contribución de los cultivos de cobertura a la sustentabilidad de los sistemas de producción”, Eds. C. Álvarez; A. Quiroga; D. Santos; M. Bodrero, Ediciones INTA, págs. 76-82. ISBN 978-987-679-177-9

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Cultivos de Cobertura

Vanzolini J.I., J.A. Galantini. 2013. Cultivos de Cobertura. Cap. 10 en Vicias: Bases agronómicas para el manejo en la Region Pampeana. (Eds. P. Renzi y M.A. Cantamutto). pags. 233-250.  ISBN: 978-987-521-470-5

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Cover Crops in the Production System

Autumn-winter cover crop effects on yield and corn N accumulation in Southwestern Buenos Aires

Cover crops (CC) have an effect on nitrogen (N) accumulation and on successive crop yields. The aim of this study was to evaluate yields, yield components and N accumulation of maize using as previous crops different CC and evaluating the response to N fertilization. Five experiments were conductedd on a Typic Argiudioll (USDA Soil Taxonomy) of Coronel Suárez. The species used as CC were: Oats (Avena sativa), Hairy vetch (Vicia sativa) and control (chemical fallow). The experimental design consisted of split-plots in three randomized complete blocks, with main plots corresponding to the cover crops treatment and subplots to the fertilizer treatment (N applied at the V4-V6 corn stage). The treatments in the main plots were the CC. The effects of CC varied according to the corn yield component.. Hairy vetch and N fertilization at different rates increased the N absorption efficiency. A greater N absorption was not always related to increases in corn yields, probably due to the climatic variability among years. There was a tendency for greater corn yields with hairy vetch as a preceding cover crop. N application reduced hairy vetch N recovery during the second year and increased N recovery during the first and third year. Fertilizer application effects varied among previous crops with a low response to N when the previous crop was hairy vetch, a variable response when in fallow and a significant response when the previous crop was oats.

Cover crops, corn, hairy vetch, clover, oats, yield, nitrogen.

Sá Pereira E. de, J.A. Galantini, A. Quiroga, M.R. Landriscini. 2014. Efecto de los cultivos de cobertura otoño invernales, sobre el rendimiento y acumulación de N en maíz en el sudoeste bonaerense. Ciencia del Suelo 32 (2) 219-231.

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Cover Crops in the Production System

Use of cover crops in soybean monoculture: effects on water and carbon balance

Cover crops (CC) are a good alternative to improve soil mulch and carbon (C) balance under no tillage with soybean monoculture (Glycine max L. Merr.), predominant in the Pampean Region. This study (2006-2011) evaluated the effect of winter CC –wheat (T), oats (A), vetch (V) and oats+vetch (A+V)- on water consumption, dry matter (MS) production and soil organic carbon contents (COT) using a control (Ct) without CC. Biomass production of the CC was closely related to rainfall recorded between the months of June and October. In general, T and A treatments contributed greater amounts of MS, on average, biomass production was 24 and 91% higher compared to A+V and V. The water cost of including CC was 13-93 mm compared to Ct. At soybean seeding, in general, Ct presented the highest water content. However, this treatment showed a loss of moisture by evaporation without biomass production, which is used by the CC to fix between 18 and 303 kg C ha^-1 mm^-1 depending on the conditions that year. The use of T, A and A+V increased the COT at a rate of 597 to 98 kg C ha-1yr-1 at 0-25 cm depth, while those without CC and with legumes (V) decreased 824 and 289 kg C ha^-1 yr^-1, respectively. For conservation or increase of the COT, use of A, A+V and T like CC would be a feasible option given that it exceeds the minimum source C input of 4.5 Mg C ha^-1 necessary to maintain the COT south of Santa Fe.

Wheat; oat; vetch; available water; total organic carbon.

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Cover Crops in the Production System

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

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Cover Crops in the Production System

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.

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Cover Crops in the Production System

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.

Vicia villosa, Avena sativa

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

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Cover Crops in the Production System

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.

Cover 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

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Cover Crops in the Production System

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.

Organic quality changes during residue decomposition

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

Cover Crops in the Production System

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.

Residue decomposition model

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

Cover Crops in the Production System

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.
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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.

Palabras clave

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.