Fertigation effects on productivity, soil nutrients and microbial population of cocoa (Theobroma cacao L.) plantation in the Western Ghats of Tamil Nadu, India

An experimental study was conducted to analyze the impact of fertigation with nitrogen (N), phosphorus (P) and potassium (K) fertilizers on soil nutrients and microbial communities in a cocoa (Theobroma cacao L.) plantation in the Western Ghats of Pollachi. The experiment followed a randomized block design with seven Fertigation treatments. Treatments included soil application (control) and twice-weekly applications of conventional fertilizers at 75 %, 100 % and 125 % of the recommended doses, along with equivalent water-soluble fertilizers (WSF). The experiment was replicated three times. With 125 % recommended dose of fertilizer (RDF) applied as a water-soluble fertilizer by fertigation, the soil provided the highest levels of N, P and K throughout the year. Applying water-soluble fertilizer and conventional fertilizers through the drip system at lower levels (75 %) resulted in much higher values of soil microbial activity. Plants receiving 100 % RDF as water-soluble fertilizer through drip fertigation recorded the highest pod counts (31.74 and 25.97 in the first year; 32.41 and 26.18 in the second year) and maximum dry bean yields (1931.69 and 1501.84 g per tree) during the respective seasons. Compared with ring basin irrigation, drip irrigation reduced N, P and K fertilizers requirements for cocoa by up to 25 % of the recommended dose.