Recycling and integrated use of agriculture based organic sources of nutrients in rainfed sunflower crop (Helianthus annus L.) in semiarid tropical Alfisol

K. Neelaveni[1], K. L. Sharma[2], K. Srinivas[3], J. Kusuma Grace[4]

Central Research Institute for Dryland Agriculture, Saidabad, Santhoshnagar, Hyderabad-59.

In order to study the scope of recycling the agricultural based organics, by way of composting and their integrated use, laboratory and green house studies were conducted at Central Research Institute for Dryland Agriculture, Hyderabad and field studies at Hayathnagar Research Farm situated at 17°18˘ N latitude, 78°36˘ E longitude.  Soils of the experimental field belong to Hayathnagar soil series (Typic Haplustalf).

The vermicompost (VC) was prepared using various treatment combinations as: i) sugarcane (Saccharum officinalis) bagasse + cattle dung; ii) sorghum (Sorghum bicolor) stover  + cattle dung; iii) vegetable waste + cattle dung; iv) fruit waste + cattle dung; v) subabul (Leucaena leucocephala) + cattle dung and vi) mixture of all these + cattle dung in the ratio of 2:1 i.e. 2 parts of the feed source and 1 part of cattle dung on weight basis. Based on the N content of vermicompost, greenhouse study was conducted using sunflower as the test crop. The Organic Carbon (OC) contents in the vermicompost prepared from sugarcane bagasse, sorghum stover, subabul loppings, fruit waste, vegetable waste and mixed feed combinations were 225.0, 243.8, 225.0, 264.0, 274.3 and 336.0 gm kg^-1 respectively. The corresponding nitrogen contents were 14.0, 12.3, 25.0, 17.5, 16.0, and 24.0 gm kg^-1 respectively. The initial C: N ratios of the feed materials varied form 10.23 to 45.50 which were reduced down to 8.4 to 19.82. Vermi compost prepared from fruit based combinations contained highest (19.3 gm kg^-1) amount of phosphorus followed by vegetable waste (14.3 gm P₂O₅ kg^-1). The VC prepared form mixed feed materials was found to be the richest in potassium content (6.3 gm K₂O kg^-1). The vermicompost prepared from mixed feed materials also contained substantial quantities of Ca (11.9 gm kg^-1) and Mg (5.5 gm kg^-1), while, Fe, Zn, Mn and Cu were found to be 17.82, 19.20, 24.60 and 7.56 mg kg^-1 respectively. While testing their efficacy under greenhouse conditions as sole application and in combination with inorganic N (1:1 ratio on N basis) as urea, using sunflower (Helianthus annuus L. var MSFH-8) as the test crop, the treatments, Urea + VC (from mixed feed material), Urea + VC (from Leucaena loppings) and urea + VC (from sugarcane bagasse) were found to be most promising from the view point of enhancing sunflower biomass yield. In addition to the compost preparation and green house studies, a field experiment was also conducted with the objective to find out the best combination of integrated nutrient use.  In this experiment, eleven treatment combinations comprising of urea @ 25, 50 and 75 kg ha^-1, vermicompost (VC prepared from only one source of feed material i.e cattle shed bed litter mixed with cowdung)  @ 50 and 75 kg N ha^-1, FYM and Gliricidia leaves + twigs alone @ 50 kg N ha^-1, and VC + fertilizer, VC + FYM and VC + gliricidia (1:1 ratio on N basis) having four replications were tested with sunflower as the test crop. Results indicated that the combination of organic and inorganic fertilizer i.e VC + fertilizer (1:1) @ 50 kg N ha^-1 produced highest kharif and rabi sunflower seed yields among all the treatments.  Use of VC + FYM, and VC +Glyricidia loppings individually also yielded almost on par with the fertilizer treatments. As computed by difference method, conjunctive use of organic + inorganic fertilizer i.e VC + fertilizer @ 50 kg N ha^-1 recorded highest Apparent Nitrogen Recovery (ANR) values of 59.02 % during Kharif and 83.28 % during rabi season among all the treatments. The ANR values were found higher in rabi than in Kharif season. Application of FYM, VC and gliricidia loppings helped in improving the organic carbon content of soil after two field crops. Among all the treatments tested, the combination of VC + Glyricidia loppings was found most effective in increasing the OC content of soil from initial level of 4.5 to 6.2 gm kg^-1 in surface soil layer (0-15 cm) and from 4.3 to 6.0 gm kg^-1 in sub-surface soil layer (15-30 cm) followed by plots receiving VC + fertilizer treatment.  This paper deals with preparation of vermicompost using different agricultural based organic materials, their efficacy, effect of integrated use of organic and inorganic sources of nutrients in appropriate proportion on sunflower crop yield under rainfed conditions, influence on soil organic matter status, soil fertility and other soil related parameters. Key words: recycling, agricultural based organics, composting, integrated nutrient use, sunflower, rainfed Alfisol, India