Crop Yield Responses to Sulfur Fertilization in Brazilian No-Till Soils: a Systematic Review

Abstract

Sulfur (S) fertilization recommendations for grain crops in Brazil were formerly established from studies on crops with a low yield potential grown on soils under conventional tillage (CT). However, the subsequent adoption of no-tillage (NT) altered S dynamics in the soil, making it necessary to carefully evaluate the applicability of these S fertilizer recommendations. In addition, the emergence of modern high-yield-potential genotypes, the successive application of concentrated low-sulfur fertilizers, and reduction in S atmospheric deposition have raised the likelihood of positive responses of crops to S fertilization. Available literature reports contrasting crop responses to S fertilization in Brazilian soils, ranging from substantial gains to slight yield losses depending on the particular crop, soil, and climate. The primary aim of this study was to examine available data for crop grain responses to S application in NT soils in order to ascertain whether existing recommendations established for Brazilian CT soils also hold for NT soils. A systematic review of data from 35 scientific publications spanning 58 crop harvests revealed a positive yield response to S fertilization in 31 % of the crop harvests, with an average yield increase of 16 %. Crops on soils with available SO 4 2--S contents above the critical level (viz., 7.5 mg dm -3 ) exhibited no positive response to S fertilization in any crop harvest (n = 18). Dry edible bean and corn were the most responsive crops, and canola and wheat, the least. For the trials with positive crop responses, a fertilizer rate of 26 kg ha -1 S sufficed to obtain at least 95 % of the maximum possible yield. In general, the S fertilization recommendations previously established for CT soil proved effective with grain crops on NT soils as a result of the critical levels of soil available SO 4 2--S and the fact that the recommended S rates are similar to those found in this study considering trials conducted under NT conditions only. However, existing recommendations could be improved by using additional criteria for soils with available SO 4 2--S contents below the critical level since a positive response was observed in 22 % (n = 18) and 92 % (n = 12) of the crop harvests under a subtropical and a tropical climate, respectively. Our results suggest that S fertilization must be prioritized in NT soils with available SO 4 2--S contents below 7.5 mg dm -3 in the 0.00-0.20 m layer, especially in tropical climate zones. In addition, regional fertilizer recommendation guidelines should consider crop type and yield expectation in order to facilitate more sustainable S management and increased crop yields in Brazil.

Gypsum Rates and Splitting Under No-Till: Soil Fertility, Corn Performance, Accumulated Yield and Profits

“…SO 4 2− is supplied by the gypsum but is weakly retained in the soil and tends to mobilize deeper into the soil profile, through the action of water and gravity, especially in NT, due to the accumulation of organic matter (OM) in the soil surface layers. Increase in OM results in a greater number of negative charges in the soil, which ends up repelling SO 4 2− , which is the main form of S available in the soil (Pias et al 2019). Up to the 0.6-m depth, a higher SO 4 2− level was observed for 3S splitting than for 1S and 2S levels, showing that the lesser the time lapse after gypsum application, the higher the level of S in the soil.…”

Does gypsum increase crop grain yield on no‐tilled acid soils? A meta‐analysis

“…This negative effect may increase with the decrease of CEC of the soil. Cereal grain yield increased by 2.4% on average even in soils with Al saturation <5%, possibly because gypsum is a source of SO 4 2− -S for crops and because sulfur is a macronutrient that increases the probability of a positive crop response in tropical and subtropical soils (Kihara et al, 2017;Pias, Tiecher, Cherubin, Mazurana, & Bayer, 2019).…”

Holistic Assessment of Biochar and Brown Coal Waste as Organic Amendments in Sustainable Environmental and Agricultural Applications

“…However, the declining levels of S are indicative of the negative impacts of continuous cropping which were not mitigated by organic amendments. Binding sites on soil colloids are preferentially bound by P as opposed to S (Pias et al 2019). A plausible explanation for the observed temporal reduction in S could be due to a lopsided competition between these elements and subsequent leaching of unbound S beyond the sampling zone considering that P was several folds higher than S in the soil.…”