ABSTRACT
Climate change events and the COVID-19 pandemic have brought to focus the significance of cassava as a supplementary food crop worldwide. However, the high yield potential of the crop necessitates timely and adequate enrichment of the soil with nutrient inputs. Consortium biofertilizers offer a viable option for reducing intensive fertilizer use to sustain soil health and productivity in cassava. The efficacy of a liquid consortium biofertilizer, specifically a plant growth-promoting rhizobacteria (PGPR) Mix - I, in economizing nutrient use in cassava was evaluated in a 4 x 3 factorial randomized block design, replicated thrice. The treatments consisted of combinations of four levels of biofertilizers and three levels of nutrients. Biometric and yield observations were recorded, and soil properties were analyzed before and after the harvest of the crop. The results showed that the liquid biofertilizer consortium at a concentration of 5% + 75% of the recommended dose, with 37.5:37.5:75 kg NPK/ha as chemical fertilizers, recorded significantly superior tuber yield in cassava. Considering the economics, the application of the PGPR liquid formulation (5%) thrice (basal, 2 and 4 MAP) along with 37.5:37.5:75 kg NPK/ha, or at a concentration of 2% with 50:50:100 kg NPK/ha, realized higher benefit-cost ratios and can be recommended for use in cassava.
ABSTRACT
Seeking to fine-tune nitrogen (N) application, increase economic returns, and decrease environmental N loss, some Arkansas rice (Oryza sativa L.) producers are turning away from blanket N recommendations based on soil texture and cultivar and using the Nitrogen Soil Test for Rice (N-STaR) to determine their field-specific N rates. In 2010, Roberts et al. correlated years of direct steam distillation (DSD) results obtained from 0- to 18-in. soil samples to plot-scale N response trials across the state to develop a field-specific, soil-based N test for Arkansas rice. After extensive small-plot and field-scale validation, N-STaR is available to Arkansas farmers for both silt loam and clay soils. Samples submitted to the N-STaR Soil Testing Lab in 2021 were summarized by county and soil texture, totaled 21 fields across 9 Arkansas counties, and were from 6 clay and 15 silt loam fields. Depressed sample submissions were again observed likely due to another wet spring and lingering effects of the COVID-19 pandemic. The N-STaR N-rate recommendations for samples were compared to the producer's estimated N rate, the 2021 Recommended Nitrogen Rates and Distribution for Rice Cultivars in Arkansas, and the standard Arkansas N-rate recommendation of 150 lb N/ac for silt loam soils and 180 lb N/ac for clay soils. Each comparison was divided into 3 categories based on a decrease in recommendation, no change in recommended N rate, or an increase in the N rate recommendation. In all 3 comparisons, county, but not soil texture, was a significant factor (P < 0.04) in observed decreases in N recommendation strategies demonstrating variations in the soil's ability to supply N across the state. Further stressing the potential N cost savings opportunities, reductions greater than 30 lb N/ac were recommended by N-STaR in 71%, 50%, and 74% of fields in the standard, estimated, and cultivar comparisons, respectively.