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Numerous studies conducted on coarse-textured soils show, significant and positive wheat yield responses when soil nitrogen (N) availability is increased, and occasional positive yield responses to sulfur (S) additions. However, the available information is not consistent for the diagnosis and analysis of the marginal contribution of S on wheat grain responses in combination with N fertilization. Thus, the objective of this study was to quantify the yield response of dryland wheat crops to N and NS fertilization and to determine the relationship between yield response and several soil properties in sandy soils. The study consisted in 34 field experiments within the semiarid and subhumid sandy pampas region (Argentina) managed under no-tillage practices. Three treatments were evaluated: i) control (without fertilization), ii) 140 kg of N ha-1 [N-NO3 soil (0-40 cm) + N fertilizer], iii) 140 kg of N ha-1 [N-NO3 soil (0- 40 cm) + N fertilizer] + 12 kg of S ha-1. A positive response to N fertilization was observed in every experimental site. Mean grain yield response to the application of N was 949 kg ha-1. Although the mean grain yield response to S fertilization was 232 kg ha-1, only 38% of the sites (13 sites) showed a significant response to this treatment. Crop response to S fertilization was not related to soil organic matter (p = 0.61), sand content (p = 0.90), soil extractable S-S042-(p = 0.29), nor soil N-N03-(p = 0.47) levels. Furthermore, it decreased with increasing maximum grain yields and it was positively related to crop responses to N fertilization. We conclude that in coarse textured soils with significant N limitations, wheat responses to S fertilization are greater and more common in low productivity sites. [ABSTRACT FROM AUTHOR]

In the sandy Pampas region, corn (Zea mays L.) grain yield is partially regulated with soil N availability levels. Although N fertilization is a common practice, available information on N fertilizers efficiency use is scarce. Our objective was to evaluate the effects of N fertilization timing on corn yield and how these effects are related to soil properties. In Typic Hapludolls located in the northern part of the sandy Pampas region, 4 field essays were performed from 2001 to 2003. Seven treatments were arranged in a factorial design with 2 main factors: (a) Urea fertilization with 0.0,37.5, 75.0 or 150.0 kg ha -1 and (b) fertilization timing (at planting or at the 6 leaves vegetative stage). Grain yields varied between 5023 and 14757 kg ha-1. No significant interactions between N fertilization rates and fertilization timing were found. Obtained results did not show differences between N fertilization at planting or during vegetative growth. Ninety percent of the maximum grain yields were achieved when available N levels (Nsoil at planting + Nfertilizer) was greater than 142 kg ha-1 in the 0 to 60 cm soil layer. The green color intensity of the upper leaves only discriminated between crops with and without N fertilization, but it was not adequate for N diagnosis. It is concluded that in Typic Hapludolls from the sandy Pampas region, fertilizer N requirements can be predicted on the basis of soil N measurements. N fertilizers could be applied both at planting or during vegetative growth stages. [ABSTRACT FROM AUTHOR]

Cover crops (CC) may offer a compelling strategy to increase the availability of nutrients, such as phosphorus (P), in agroecosystems where continuous extractive agriculture has resulted in a depletion of soil fertility. Our objective was to analyse the long-term effect of CC incorporation in soybean-based crop sequences on: i) organic and inorganic P fractions (P inorg and P org), ii) extractable inorganic P (P Bray), and iii) biochemical soil properties associated with P mineralization (monophosphatase activity and P org in the coarse fraction (P org -CF)) in soils with contrasting P availability and under different edaphoclimatic conditions. A factorial design was performed evaluating two sequences (continuous soybean (Sb) or CC/Sb) and two fertilization treatments (with or without P fertilization, +P and 0 P, respectively). In general, the long-term annual implementation of CC tended to decrease inorganic P fractions (P inorg and P Bray), and the magnitude of this effect was more marked when P availability was low (0 P). However, in treatments where P was applied, the use of CC did not modify P Bray. The effect of CC on organic P fractions was greater than that of P fertilization. Increases of up to 63 kg P org ha−1 were determined when including CC, whose magnitude was unrelated with soil texture. Cover crops also increased P org -CF and monophosphatase activity. Our results demonstrate that, despite decreasing inorganic P fractions, CC have beneficial effects on biochemical variables associated with P mineralization, which is an essential process for crops nutrition. • We studied cover crops (CC) and fertilization effects on P fractions. • The CC tended to decrease inorganic P, especially in low P availability conditions. • The CC had a greater effect on organic P fractions than P fertilization. • Monophosphatases and organic P in the coarse fraction increased in CC treatments. [ABSTRACT FROM AUTHOR]

Water and nitrogen (N) are the main factors that generate the greatest limitations in food production. The use of cover crops (CC) due to their multiple benefits, can modify soil water and nitrate dynamic. It is therefore important to know the interaction between cash crops and CC. The objectives of this work were to evaluate the interaction between rye as CC and cash crops over the dynamics of water and N; and the synergy between crops. For these objectives, samples were taken to measure soybean and corn yield and rye dry matter production (DM) and soil samples to measure evolution of the water content and available N as nitrate due to the presence of the different crops in a long-term experiment located in General Villegas (Buenos Aries) during the 2010/11, 2011/12 and 2012/13 period. As a result, the DM production of the CC was increased (between 30 and 150%) with soybeans as a predecessor and when it was fertilized. No differences in general were observed in the availability of water due to the use of CC. Regarding the concentration of N in soil, it was observed a decrease of it concentration probably due to the consumption of CC in the soybean treatments. Finally, the yields of cash crops in general were not affected, except for a single year where corn production was statistically higher in the treatment without CC (between 1000 and 2000 kg ha-1). Therefore, it is necessary to adjust CC management according to climatic situations and the cash crop. [ABSTRACT FROM AUTHOR]

Cropping systems based on a single crop per year, such as soybean monoculture, result in an inefficient use of available resources and low productivity, and are usually related with a negative environmental impact. The intensification of soybean-based cropping sequences can increase resource productivity, enhancing the sustainability of the production systems. This study aimed to analyse the long-term effect of intensification practices in soybean-based sequences on: i) water and radiation productivity, and ii) soybean yield, in four temperate and fully humid environments with contrasting soil texture. The study was carried out in four long-term experiments where three cropping sequences were evaluated: soybean monoculture, cover crop (CC) / soybean, and a three-year crop rotation including wheat (Triticum aestivum L.), maize, CC, and soybean. Oat (Avena sativa L.), triticale (x Triticosecale Wittmack), wheat, or rye (Secale cereale L.), were used as CC. Four 3-yr rotation cycles were evaluated between 2007 and 2018. Intensification of cropping sequences increased soybean yield (17%) in one out of four sites, and did not significantly change in the other three sites. Soybean yield varied among cycles at all sites and was positively associated with rainfall during the growing season (r = 0.81). Intensified sequences increased over 40% both water and radiation productivity as compared with soybean monoculture. Despite the different edaphoclimatic characteristics of the evaluated locations, the magnitude of the improvement in the productivity of the resources resulting from the intensification of cropping sequences was similar at all sites. Therefore, in temperate and fully humid environments with contrasting soil texture, the intensification of soybean-based sequences with grasses, CC, and double crops is a feasible alternative to increase the productivity of resources without compromising soybean yield, hence, it should be taken into account by government organizations when developing policies. • We studied intensification practices long-term effects on water and radiation productivity and soybean yield. • Intensified sequences increased > 40% water and radiation productivity as compared with soybean monoculture. • Intensified cropping improved productivity equally at different sites despite varying edaphoclimatic traits. • Soybean yield was either increased (n = 1, +17%) or unaffected (n = 3) by the intensification of cropping sequences. [ABSTRACT FROM AUTHOR]