Effect of integrated soil fertility management on hydrophysical soil properties and irrigated wheat production in the upper Blue Nile Basin, Ethiopia

In Ethiopia, soil fertility problem caused by acidity substantially limits agricultural productivity, necessitating sustainable integrated nutrient management. This study assessed the effect of combined application of lime, manure and inorganic fertilizer on selected hydrophysical properties of an acid clay Nitisols in the Koga irrigation scheme, Ethiopia. Five levels of integrated soil fertility management treatments were tested for four consecutive cropping seasons: (i) 0.86 t ha(-1) lime combined with 3 t ha(-1) manure and full-dose inorganic (urea and NPS-B) fertilizer (L3); (ii) 1.15 t ha(-1) lime combined with 3 t ha(-1) manure and full-dose inorganic fertilizer (L2); (iii) 1.43 t ha(-1) lime combined with 3 t ha(-1) manure and full-dose inorganic fertilizer (L1); (iv) 3 t ha(-1) manure combined with full-dose inorganic fertilizer (M); and (v) full-dose inorganic fertilizer alone (C) as a control. Undisturbed soil samples were collected at 0-10 and 10-20 cm soil depths and analyzed to determine saturated hydraulic conductivity (Ks), soil-water retention characteristics, total porosity and bulk density. Disturbed soil samples were collected at the same depths to analyze soil organic carbon and texture. Infiltration capacity measurements and visual evaluation of soil structural quality were done in the field. Significantly higher (P < 0.05) soil organic carbon was found at L1, L2, L3 and M compared with C. The application of L1, L2, L3 and M reduced bulk density compared with the C. The amount of water retained at field capacity (FC) was significantly (P < 0.05) affected by the treatments in the order of L1 > L2 > M > L3 > and C for both soil depths 0-10 and 10-20 cm. The Ks under plots treated with L1 was 64% and 37% higher than that of C for the 0-10 and 10-20 soil depths, respectively. Significantly (P < 0.05) higher infiltration capacity was found at L1 (0.007 cm min(-1)) followed by L2, L3 and M (0.006 cm min(-1), 0.006 cm min(-1), and 0.005 cm min(-1)) compared with C (0.004 cm min(-1)), respectively. Good soil structural quality (Sq) score was identified in L1, L2, L3 and M, whereas in C poor Sq score was found. As compared with C, grain yield was improved by 69% at L1, 59% at L2, 53% at L3, and 44% at M during 2018 and by 70% at L1, 58% at L2, 55% at L3 and 46% at M in 2019. In conclusion, the application of organic manure combined with lime and inorganic fertilizer enhanced the infiltration rate, water holding capacity and grain yield more than the inorganic fertilizer application alone. There was also a significant effect of liming as such, with the highest doses showing the best results.

Automated summary

In Ethiopia, the problem of soil fertility caused by acidity significantly limits agricultural productivity. This study examined the impact of using a combination of lime, manure, and inorganic fertilizer on the hydrophysical properties of acid clay Nitisols in the Koga irrigation scheme. The results showed that the combined application of organic manure, lime, and inorganic fertilizer enhanced the infiltration rate, water holding capacity, and grain yield of the soil.