Effects of integrated fertilization on soil sustainability and cassava (Manihot esculenta Crantz) yield in an ultisol

Abstract

The present study aimed to assess the effects of integrated fertilization on soil and cassava yield. A randomized complete block design (RCBD) was used in the 24 x 5 factorial. Factor A comprised 24 cassava genotypes, while Factor B comprised five fertilizer treatment rates (2.5 t/ha poultry manure (PM) + 300 kg/ha NPKMg, 5 t/ha PM + 200 kg/ha NPKMg, and 7.5 t/ha PM + 100 kg/ha NPKMg), 400 kg/ha NPKMg fertilizer, and control. Integrated fertilizer application improved soil fertility compared to 400 kg/ha NPKMg and control treatments. Integrated fertilization of 7.5 t/ha PM and 100 kg/ha NPKMg had a 16–26% and 15–25% significant increase in soil pH compared to other treatments, respectively. Application of 7.5 t/ha PM + 100 kg/ha NPKMg had significant organic matter content at harvest (2.92 and 3.11%) compared to initial values of 1.37 and 1.55%. The treatments of 7.5 t/ha PM and 100 kg/ha NPKMg had (30-88% and 30-87%) and (8-94%, and 11- 91%) higher organic matter and N than other treatments at harvest. Significant differences (P<0.05) were observed in storage root yields. The NR07/0240 produced significant storage root yields of 34.41 and 34.12 t/ha in both cropping seasons. Obubit Okpo had the least yield: 7.34 and 6.55 t/ha. Treatment with 7.5 t/ha PM and 100 kg/ha NPKMg out-yielded other fertilizer treatments, while control had the least storage root yield. The result revealed that treatments with integrated fertilizers had lower soil pH, significantly higher total N, organic matter, and exchangeable bases at harvest.