Effect of mineral fertilizer, farmyard manure, and compost on yield of bread wheat and selected soil chemical properties in Enderta District, Tigray Regional State, Northern Ethiopia

Abstract

Soil nutrient depletion as a result of continuous cultivation of the land without adequate addition of external fertilizer inputs is one of the major problems that constrain the yield of bread wheat and sustainable productivity of the soil in Tigray Regional State. A field experiment was conducted to elucidate the effect of mineral nitrogen and phosphorus fertilizer (NP), farmyard manure (FYM), and compost on the productivity of bread wheat and selected soil chemical properties. The treatments consisted of three bread wheat varieties (Kakaba, Paven 76, and Mekelle I) and eight fertilizer combinations [control (0, 0), blanket recommended NP fertilizer (RNP) (41 kg N ha^-1 + 46 kg P₂O₅ ha^-1), 10 t ha^-1 FYM, ½ of RNP (20.5 kg N ha^-1 + 23 kg P₂O₅ ha^-1) + 10 t ha^-1 FYM, ½RNP (20.5 kg N ha^-1 + 23 kg P₂O₅ ha^-1) + 5 t FYM ha^-1, 7 t compost ha^-1, ½ RNP (20.5 kg N ha^-1 + 23 kg P₂O₅ ha^-1) + 7 t compost ha^-1, and ½ RNP (20.5 kg N ha^-1 +23 kg P₂O₅ ha^-1) + 3.5 t compost ha^-1]. The experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. Data were collected on yield and yield components of the crop and selected soil chemical properties, namely, contents of soil organic carbon (OC), available phosphorus (P), total nitrogen (TN), cation exchange capacity (CEC), soil reaction (pH), and electric conductivity (EC). The results revealed that the yield and yield components of wheat significantly (P ≤ 0.01) responded to application of the fertilizers. Combined application of 10 or 5.0 t ha^-1 FYM with half of
the recommended mineral nitrogen and phosphorus fertilizer (i.e., 20.5 kg N + 23 kg P₂O₅ ha^-1) increased grain yield of the crop by 185 and 170%, respectively, over the control treatment. Similarly, combined application of 7.0 or 3.5 t ha^-1 compost with half of the recommended mineral nitrogen and phosphorus fertilizer (20.5 kg N + 23 kg P₂O₅ ha^-1) increased grain yield significantly by 159 and 148%, respectively, over the control treatment. The highest net benefits of 37290 ETB, 33002 ETB, and 30835 ETB ha^-1 with acceptable marginal rates of return were obtained in response to applying half of the blanket recommended miner NP fertilizer (½ RNP) ha^-1 + 5 t FYM ha^-1 to Kakaba, Mekelle I, and Paven 76, followed by application of the full blanket recommended NP fertilizer (RNP) ha^-1 and ½ RNP ha^-1+ 5 t ha^-1 compost. It is, thus, concluded that combined application of half of the blanket recommended NP fertilizer (20.5 kg N + 23 kg P₂O₅ ha^-1) with 5 t FYM ha^-1 compost led to the most economically optimum bread wheat yield as well as improved soil physico-chemical properties for sustainable production of the crop in the future. Analysis of the selected soil chemical properties at harvest indicated that, compared to the available phosphorus and total nitrogen contents of the soil in plots to which no any fertilizer was applied (control treatment), the total nitrogen and phosphorus contents of the soil to which 10 t ha^-1 FYM and 7 t ha^-1 compost were applied increased by about 100% whereas that of organic matter increased by about 300%. The results indicate that the soils of the study area are deficient not only in mineral nutrients such as nitrogen and phosphorus but also in soil organic carbon and its constituents that are important to maintain soil quality and health. This implies that there is a need for judicious soil ameliorative measures using both mineral and organic fertilizers to enhance productivity of crops in the region.

Keywords: Blanket recommended NP (RNP) fertilizer; Compost; Economic analysis; Farmyard manure; NP fertilizer; Bread wheat variety; Triticum aestivum L; Yield