Soil Physicochemical Properties and Rhizosphere Biota of Sorghum as Influenced by Rice Crop Residue Management Techniques and Nitrogen Levels

Abstract

The current investigation was conducted on a sandy clay loam soil at the Agricultural College Farm, Bapatla, during the rabi season of 2021–2022, to examine the impact of different nitrogen levels and rice crop residue management strategies on soil physicochemical properties and rhizosphere biota of sorghum. Because the grain is frequently caught in constant rain, which causes grain molds to damage its quality, sorghum harvested during the rainy season is mostly used as feed and for other industrial purposes. But because of its high grain quality, post-rainy sorghum is mostly consumed as food. It is also a major source of stover, particularly in dry seasons. The area planted to sorghum has drastically decreased, particularly during the rainy season. However, post-rainy sorghum has remained relatively stable and is primarily grown in three districts of Karnataka (Bijapur, Gulbarga, and Raichur) and six districts of Maharashtra (Solapur, Ahmednagar, Pune, Beed, Osmanabad, and Aurangabad), in addition to portions of Andhra Pradesh and Tamil Nadu. The experiment was laid out in split-plot design with four rice crop residue management techniques (M1: No residue, M2: Burning of residue, M3: Incorporation of residue with rotovator without application of ANGRAU decomposer and M4: Incorporation of residue with rotovator after application of ANGRAU decomposer as main plot treatments and four nitrogen levels (Control, 40 kg ha−1, 80 kg ha−1and 120 kg ha−1) as sub plot treatments. Among soil physico chemical properties, pH, EC and available phosphorous did not differ significantly among the rice crop residue management techniques and nitrogen levels whereas the highest soil organic carbon, available nitrogen and available potassium were obtained with incorporation of residue with rotovator after application of ANGRAU decomposer (M4). Soil rhizosphere biota was significantly influenced by rice crop residue management techniques and was not influenced by nitrogen levels. Mean values for rice crop residue management techniques revealed that highest bacterial population was observed with incorporation of residue with rotovator after application of ANGRAU decomposer (M4) and lowest bacterial population was observed with burning of residue (M2). Highest fungal population was observed with incorporation of residue with rotovator after application of ANGRAU decomposer (M4) and lowest fungal population was observed with no residue (M1) which was on par with burning of residue (M2). Highest actinomycetes population was observed with incorporation of residue with rotovator after application of ANGRAU decomposer (M4) which was on par with incorporation of residue with rotovator without application of ANGRAU decomposer (M3) and lowest actinomycetes population was observed with burning of residue (M2) which was on par with no residue (M1).