Soil enzyme activities as influenced by natural, organic and recommended farming practices of cotton crop in cotton + greengram intercropping system

Abstract

A field experiment was conducted during Kharif 2021-22 at Natural Farming Project plot number E 131 of Main Agricultural Research Station, UAS, Dharwad during 2021-22 on clay soils to study the effect of different farming practices and foliar application of different organic liquid manures on soil enzyme activity of cotton rhizosphere. Experiment was laid out in split plot design with twelve treatments replicated thrice with uneven control (RPP). The main plots includes two farming practices such organic farming (OF: M1) and natural farming (NF: M2), in sub plots consists of foliar application of liquid organic formulations (Cow urine (CU) @ 50%, Jeevamrutha (JM) @ 100%, Vermiwash (VW) @ 10%, Gokrupamrutha (GK) @ 20%, sequential application of CU- JM- VW- GK-VW at 21, 42, 63, 84, 105 and 126 DAS (6 times) in cotton and foliar application of Jeevamrutha as per ZBNF recommendations (5%, 7.5% and 10% at vegetative, flowering and boll formation stage in cotton starting from 21 DAS). Organic farming practice recorded higher dehydrogenase (69.41 and 64.35 µg TPF formed g-1 soil day-1), phosphatase (259 and 239.33 NH4- N g -1 of soil day -1) and urease activity (16.31 and 14.46 pNP formed g-1 soil hr-1) at 90 DAS and harvest. Further foliar application of Jeevamrutha @100% recorded higher dehydrogenase (73.59 and 68.25 µg TPF formed g-1 soil day-1), phosphatase (277.59 and 260.93 NH4- N g -1 of soil day -1) and urease activity (17.28 and 14.64 pNP formed g-1 soil hr-1). However, when compared with RPP, foliar application of Jeevamrutha @ 100% in organic farming recorded highest dehydrogenase (73.59 and 68.25 µg TPF formed g-1 soil day-1), phosphatase (277.59 and 260.93 NH4- N g -1 of soil day -1) and urease activity (17.28 and 14.64 pNP formed g-1 soil hr-1) at 90 DAS and at harvesting stage of cotton.