Synergism of sulfur availability and agronomic nitrogen use efficiency

Nutrient management strategies that exploit nutrient elements’ synergistic interaction to enhance nitrogen use efficiency (NUE) are needed for economic and environmental reasons. A field study was carried out during the 2020–2022 growing seasons at six locations in three countries: two each in the United States, Ghana, and Mali using three sulfur (S) sources with different bioavailability levels (micronized elemental S, untreated elemental S, and ammonium sulfate); applied at five S application rates: site-specific recommended S rate (SR), 25%, 50%, 75%, and 125% of SR; and a single nitrogen (N) application rate (site-specific recommended N rate) to comprehensively investigate the influence of S availability on NUE. Specific objectives were to evaluate the impact of S availability on corn (Zea mays L.) yield, N uptake, and NUE. Regardless of the S source and experimental site, the aboveground S and N uptake were strongly and positively correlated (r > 0.88). Increases in apparent N recovery efficiency and agronomic NUE occurred with corresponding increases in S application rate, irrespective of the site and S source. The combined data showed that the agronomic efficiency of applied N fertilizer sources could be enhanced significantly by increasing S availability in soils. With the rising N fertilizer costs in recent times, N losses from the applied fertilizer are a drain on farmers’ income and of environmental concern. Thus, increasing NUE is a needed strategy to safeguard against excessive N application, increase farm profits, and minimize N losses to the environment that could disrupt the ecosystem function

Improving agronomic effectiveness of elemental sulfur to increase productivity in sulfur-deficient soils

Elemental sulfur (ES), a byproduct of oil and gas processing, could be an alternate sulfur (S) fertilizer source for crop production if its bioavailability is improved. Increasing the specific surface of ES by reducing its particle size can accelerate ES oxidation to enhance its bioavailability. In field trials at six locations across three countries: two each in the United States, Ghana, and Mali, we determined the agronomic effectiveness of micronized ES (MES). Specific objectives were to quantify (i) corn (Zea mays L.) productivity, (ii) S recovery, and (iii) residual soil S concentration; following MES application, compared to ammonium sulfate (AS), a commercially available sulfate fertilizer, at four application rates—(i) locally recommended sulfur application rate (SR), (ii) 50%_SR, (iii) 75%_SR, and (iv) 125%_SR—and a control where no S was applied. Averaged across all sites and in the three growing seasons, AS at 50%_SR increased corn yield by ≤8% relative to control. Increasing to 75%_SR, SR, and 125%_SR resulted in 12%, 26%, and 28% yield increases, respectively. Applying MES at 50%_SR increased yield by ≤6%, and at 75%_SR, yield increased by ≤26%. Increasing the S application rate to SR and 125%_SR resulted in marginal yield increases. The combined data suggest that MES can be applied at a reduced rate of 75_SR to achieve similar yields as AS applied at SR. We conclude that MES could be an efficient S fertilizer alternative. However, economic analysis is needed to determine the potential profitability of using MES fertilizer products for crop production

Nitrogen Fertilization Effect on Phosphorus Remediation Potential of Three Perennial Warm-Season Forages

Warm-season C-4 grasses are capable of removing excess soil nutrients because of their high Yield potential and nutrient uptake efficiency. Bahiagrass (Paspalum notatum Flugge), limpograss [Hemarthria altissima (Poir.) Stapf& Hubb], and stargrass (Cynodon nlemfuensis Vanderyst), three commonly used pasture grasses in South-Central Florida, were grown to examine the effect of increasing N rates on herbage production and soil P removal. Nitrogen was applied at rates of 67,90, and 134 kg N ha(-1) harvest(-1), representing 1, 1.3, and 2 times the recommended N fertilizer application rate for hay production. During 3 yr of evaluation, all three grasses showed a positive P-removal potential that increased with increasing N fertilizer application. Phosphorus removed by forages over the 3-yr period for the highest N application rate was 106, 132, and 147 kg ha(-1) for limpograss, bahiagrass, and stargrass, respectively. Mehlich 1 extractable P from the Ap horizon of all plots decreased by as much as 80% of the initial P load over the study period; only similar to 15 to 17% of which appeared to leach to subsurface horizons. Nitrogen application enhanced P uptake and consequently reduced P transport to deep (>13 cm) soil depths. These data indicate that stargrass, bahiagrass, and limpograss managed intensively for hay production represent effective options in removing excess soil P from P-impacted sites