Nutrient status of soil after maize harvest and uptake of stover influenced by fertilizers, biochar and humic acid application

Abstract

A field study was carried out at college farm, College of Agriculture, Rajendranagar, Hyderabad, Andhra Pradesh during Kharif 2013 to evaluate combined application of biochar with humic acid as a fertility amendment at varied fertiliser levels. The experiment was laid out in a Randomized Block Design and replicated thrice with three factors comprised of factor-I (fertilizers- 100 % RDF and 75 % RDF), Factor-II (biochar levels- 0, 5 and 7.5 t ha-1) and Factor-III (humic acid levels of 0 and 30 kg ha-1). Soil had a pH of 7.72, EC of 0.217 dS m-1 with low organic carbon (0.49%) and available nitrogen (138.6 kg ha-1), high available phosphorus (31.28 kg ha-1) and potassium (629 kg ha-1) and sufficient available sulphur (28 ppm). After maize harvest, nutrient status of experiment site was analyzed. Recommended dose of NPK along with biochar at 7.5 t ha-1 and humic acid at 30 kg ha-1 was recorded significantly highest available N (182 kg ha-1) and P (66.5 kg ha-1). In case of potassium, 75% NPK alone recorded highest (533 kg ha-1) followed by 75% NPK with @ 7.5 t ha-1 biochar (476 kg ha-1). Recommended dose of NPK and 75% NPK along with biochar at 7.5 t ha-1 and humic acid at 30 kg ha-1 were at par in available sulphur. High nitrogen, phosphorus and sulphur uptake was obtained with application of recommended NPK along with biochar at 7.5 t ha-1 and humic acid at 30 kg ha-1, whereas uptake of P was highest with reduced NPK along with biochar @ 5 t ha-1 and humic acid at 30 kg ha-1.