Response of cowpea (vigna unguiculata l.) to organic and chemical fertilizer applications on grain yield and yield components

Abstract

Grain of cowpea are used for human diet and its grain contains high protein, minerals and vitamins. Cowpea was also used as hay, silage, green forage, grain fodder for feed livestocks. The experiment was conducted under irrigated conditions in the experimental area of Field Crop Deparment, Faculty of Agriculture, Cukurova University, Balcalı, Adana, Turkiye. The growing period covered throughout 2021 and 2022. The field experiment was organized in split plots based on randomized complete blocks design with three replication. Two registered cultivars (Karagöz ve Akkız) were used as a research material. In this experiment the main plots were cultivars and sub-plots were application of fertilizer. Treatments were: control (no fertilizer), solid leonardite, liquid leonardite, basal chemical dose + solid leonardite, basal chemical dose +liquid leonardite, basal chemical fertilizer + additional N fertilizer. Basal chemical dose was application of 40 kg N ha-1 and 100 kg N ha-1 P2O5 (Di ammonium phosphate or DAP) before sowing as recommended chemical fertilizer. Addition chemical dose was application of 80 kg N ha-1 (Ammonium sulfate) over the basal dose at the seedling stage. Rhizobia inoculant was not applied during the field experiment. Akkız seed yield was significantly higher in application of liquid leonardite fertilizer and the combination of basal chemical fertilizer + liquid leonardite fertilizer with 1656 and 1533 kg ha-1 respectively, compared to other treatments. The grain yield in the control plot was the lowest in both cultivars. As a result, applying liquid leonardite fertilizer into the soil before sowing can be useful for grain production in cowpea.