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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