Nutrient Inputs for Rehabilitation of Non-responsive Soils in the Guinea and Sudan Savannah Agroecological Zones of Ghana: Impact on Grain Yield and Soil Quality

Abstract

Studies have shown that the continuous application of N, P, and K fertilizers has led to the depletion of secondary and micronutrients, which have become limiting nutrients hindering crop growth and yield. An on-farm trial was conducted to determine the effect of site-specific nutrient fertilizers and compost on soybean yield, phosphorus use efficiency, and soil properties, at Nyong Guma, Serekpere, Daffiama Saapare, and Naaga in northern Ghana. Nine (9) treatments (3 rates of mineral fertilizer × 3 rates of FertiSoil) were applied in a factorial combination arranged in randomized complete block design with three replications. On average, the soybean grain yield increased significantly with the combined application of FertiSoil and mineral fertilizer at full rates at Nyong Guma, Serekpere, and Naaga from <1,000 kg ha−1to > 1,500 kg ha−1. The co-application of 50% recommended rate (RR) of mineral fertilizer and 5 t ha−1FertiSoil increased soybean grain yield by over 250% at Daffiama Saapare. The application of 50% RR mineral fertilizer significantly increased phosphorus use efficiency by 5–55% compared to its combination with FertiSoil or FertiSoil alone at different rates across locations. Incorporation of 5 t ha−1FertiSoil and 100% RR mineral fertilizer significantly increased exchangeable K, Ca, and Mg, and microbial C and P by 0.33, 2.84, 0.56 cmol(+)kg−1and 102.7, 33.37 mg kg−1, respectively, at Serekpere. The combined application of 5 t ha−1FertiSoil and 50% RR mineral fertilizer relatively increased soil organic C (42%) and available P (12%) at Naaga. The soil quality index revealed that the addition of 5 t ha−1FertiSoil to 100% RR mineral fertilizer was the most sustainable nutrient management option across the study sites. Sole mineral fertilizer treatments at 50% RR were the most profitable in all the study locations ranging from value cost ratio (VCR) of 2.7–7.6. The application of limiting nutrients and organic amendments serves as an efficient nutrient management option to improve soil health, crop production and economic profitability on smallholder non-responsive soils.