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Birsa Agricultural University, Ranchi

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Subject: Soil Science and Agriculture Chemistry × Author: Minz, Asisan × Start date: 2013 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    IMPACT OF CROP RESIDUES AND NUTRIENT COMBINATIONS ON SOIL HEALTH AND PRODUCTIVITY UNDER MAIZE–WHEAT CROPPING SYSTEM
    (Birsa Agricultural University, Ranchi, 2021) Minz, Asisan; Kumar, Rakesh
    Maize-wheat is the third most important cropping system in India (1.8 m ha) and second most important in Jharkhand. Both the crops are fertilizer responsive and exhibit full yield potential when supplied with adequate quantities of nutrients at proper time. But poor economic resources of the Jharkhand farmers compel to go for imbalance fertilizer use leading to deterioration of soil fertility and crop productivity. Considering this fact, an experiment was conducted in farm area of Soil Science and Agricultural Chemistry, Birsa Agricultural University, Ranchi, during the year 2016-17 & 2017-18 to study the ―Impact of Crop Residues and Nutrient Combinations on Soil Health and Productivity under Maize – Wheat Cropping System‖. Plant samples were collected at different growth stages of crops viz., maize-V4, V10 and at harvest &wheat-CRI, PI and at harvest. Soil samples at two depths 0-15 and 15-30 cm were collected at different growth stages of crops for analysis physico-chemical and biochemical properties (pH, total N, organic carbon, available N, P&K, soil microbial population and enzymatic activities). The treatments comprised of two levels of crop residues i.e., with crop residues and withoutcrop residues along with five levels nutrient combinations i.e., T1 - ample NPK (250: 120: 120 kg/ha), T2 - omission of N with full P and K (-N = 0: 120: 120 NPK kg/ha), T3 - omission of P with full N and K ( -P = 250: 0: 120 NPK kg/ha), T4 - omission of K with full N and P (-K = 250: 120: 0 NPK kg/ha) & T5 - SSNM (200: 90: 100 NPK kg/ha) for maize in kharif season. The corresponding treatments for wheat in rabi season were (T1= NPK) 150: 110: 100 kg/ha, (T2 = -N) 0: 110: 100 NPK kg/ha, (T3 = -P) 150: 0: 100 NPK kg/ha, (T4 = -K) 150: 110: 0 NPK kg/ha and (T5 = SSNM) 120: 70: 60 NPK kg/ha. The experiment was replicated four times in Randomized Block Design (RBD). The experiments were initiated in the year 2009 and modified during 2011-12, with above mentioned treatments. The available N, P, K and organic carbon before starting experiment (2009) was 182.43, 13.40, 133.52 kg/ha, and 3.80 g/kg, respectively, with pH 5.53. The experiment continued to the initial physico-chemical properties were evaluated before present studies i.e., 2015 with pH 5.35-5.73, available N (173.11-201.34 kg/ha), P (12.36-31.10 kg/ha), K (108.44-218.72 kg/ha) and organic carbon (3.90-4.10 g/kg). The result showed that with crop residues incorporation, maximum grain yield of both maize and wheat recorded under NPK treated plot with crop residue (75.76 and 51.48 q/ha, respectively) was higher as compare to nutrient omission plots, and followed by SSNM (65.35 and 49.14 q/ha for maize and wheat crops, respectively). However, with respect to system yield, NPK was higher than the SSNM treatment. Reduction in system yield was highest in N omission plots (112%) followed by P (62%) and K omitted plot (27%) with incorporation of crop residues, whereas, without incorporation of crop residue followed the order N (98%), P (47%) and K (33%). Nutrient concentration, uptake and total uptake varied with the treatments, maximum N, P and K uptake were found with the application of NPK under maize-wheat cropping system with incorporation of crop residue. Omission of nutrients influenced the fertility of soil with respect to soil organic carbon and available N, P and K values, which were maximum under application of NPK along with crop residues. Highest microbial count for bacteria (81.88 x 106 /g soil), Fungi (99.50 x 104 and Actinomycetes (12.50 x106 /g soil), were recorded for treatment which received crop residue along with NPK fertilizers, at peak growth period (V10 stage) of maize crop. Similarly under wheat crop‘s soil sample the maximum count for bacteria (67.88 x 106 /g soil), Fungi (78.75 x 104 and Actinomycetes (12.25 x106 /g soil), were registered at PI stage of wheat under NPK + crop residue treatment. The urease enzyme activity varied from (0.13 to 0.37 μg urea hydrolysed g/ soil /hr) and (0.11 to 0.32 μg urea hydrolysed g/ soil /hr), dehydrogenase activity (13.12 to 47.92 μg TPF /g/d) and (8.43 to 43.54 μg TPF /g/d) and concentration of acid phosphatase (70.65 to 221.66 μg p–nitrophenol /g/d) and (60.53 to 199.92 μg p–nitrophenol /g/d) with and without incorporation of crop residues, respectively, in maize crop. The highest status of urease activity (0.33 μg urea hydrolysed g/ soil /hr) and dehydrogenase activity (46.76 μg TPF /g/d) at PI stage of wheat crop, under treatment NPK along with crop residue, while the highest acid phosphatase activity was registered at CRI stage (205.74 μg p–nitrophenol /g/d) of wheat under same treatment. Maize grown with NPK (250:120:120 kg/ha) recorded maximum gross return (Rs./-105396 per ha), net return (Rs./-78932 per ha) and B:C ratio (2.98), while, under wheat grown with 150:110:100 kg/ha recorded maximum gross return (Rs./-85085 per ha), net return (Rs./-55812 per ha) and B:C ratio (1.91) were recorded with crop residue incorporation plot. Similarly, economic analysis of whole system (maize-wheat) showed that application of NPK the B:C ratio was (2.71) along with incorporation of crop residues. Increment in B:C ratio and net return in all (N and P, except K) omission plots was recorded in maize-wheat sequence with incorporation of crop residues. There was 12% increase of Apparent Recovery Efficiency (ARE) of applied N and 23% for applied K under maize-wheat cropping system with incorporation of crop residues. Per cent applied N fertilizer that was taken up by the crop (apparent recovery of applied N) was higher in wheat crop with crop residue as (57%) as compared to without crop residue (46%). The Nitrogen internal use efficiency of maize, wheat and maize-wheat cropping system was (39.14 & 40.54), (46.59 & 50.73) and (87.93 & 95.84 kg grain yield per kg N applied) with and without incorporation of crop residues. Correlation study showed a highly significantly and positively correlated among all the chemical and biological properties of soil with incorporation of crop residue. The soil organic carbon was positively correlated with urease enzyme (r = 0.988** & r = 0.982**), yield (r = 0.987** & r = 0.914*), available N (r = 0.964** & r = 0.945*), bacteria (r = 0.923* & r = 0.941*) and actinomycetes (r = 0.956* & r = 0.954*) with and without incorporation of crop residues. Available N content of soil was positively correlated with bacteria (r = 0.983** & 0.995**), urease (r = 0.963** & r = 0.978**), dehydrogenase enzyme (r = 0.971** & r = 995**), actinomycetes (r = 0.992** & r = 0.997) and yield (r = 0.976** & r = 0.916*) with and without incorporation of crop residue. The concentration of urease was positively correlated with yield (r = 0.977** & r = 0.954*) and dehydrogenase enzyme (r = 0.947* & r = 0.981**) with and without incorporation of crop residues. Dehydrogenase enzyme was significantly & positively correlated with yield (r = 0.923* & r = 0.929*) with and without incorporation of crop residues. The regression equation explained 98.6 % variations in grain yield of maize due to combined effect of available N and P. When all the independent variables (available N, P and K) were considered together in the regression equation, the predication value was 99.8% with non-significant effects of available P and K for wheat crop. Elimination of available P from the regression equation suggested that the decrease in prediction value was about 0.8%in wheat yield. Straw incorporation into the soil is considered to be an important strategy to improve soil fertility and to reduce the dependence on mineral fertilization. On the basis of above findings it may be concluded that balance fertilization with incorporation of crop residue in long-term maize-wheat cropping system maintained maximum individual crop yield as well as system yield and gave profitable economy return and improved the soil health.