Kumar, VipinBORPATRAGOHAIN, BIDISHA2023-10-202023-10-202021D/SS/402/2018-19https://krishikosh.egranth.ac.in/handle/1/5810199579The dominant agricultural system prevailing in the Indo-Gangetic Plain is the cereal based cropping system comprising of rice-wheat. Soil quality and health is in the limelight and considered as a vital component of conservation agriculture towards agricultural sustainability. The main challenges confronted by the farming community of Indo-Gangetic Plain (IGP) in Bihar under intensive conventional tillage rice-wheat based cropping system are shortage of manpower, water, energy; high cost of production, diminishing farm returns and unpredictable climatic conditions. To address these loopholes of conventional system, conservation agriculture management systems of crop production are being established. The implementation of conservation agriculture centered on least soil manipulation, surface crop residues retention with practical crop rotation is the need of the hour. The goal of our research was to study how crop establishment and residue management affected soil health indicators, and yield as well as different fractions of the macronutrients (N, P, K and S) through various crop establishment, tillage practices and crop residue combinations in the cropping system of rice-wheat. A long term experiment was established in collaboration with CIMMYT, India, since Monsoon, 2006 with eight different tillage, crop setup, and residue management combinations. The study was performed during 10th June 2019 to 12th October 2019 and 14th November 2019 to 25th March 2020 (two seasons). The site experiences hot and humid summers and has cold winters. The average rainfall of 1344 mm, 89.7 % (1107.8 mm) of which receives throughout the time of monsoon (mid-June to mid-September) while, the winter North-East monsoon rains are scanty and received during January-February. The soil of the experimental site belongs to order Entisol, texture being sandy loam with alkaline pH (8.86), medium SOC (0.48 %) and soil available N, P, K (205.62, 9.35, 136.10 kg ha-1). The trial was set up Randomized Block Design having eight treatment details replicated thrice within a block. The treatments were: puddled transplanted rice-conventional tillage wheat (T1); Puddled transplanted rice-zero tillage wheat (T2); Zero tillage rice-zero tillage wheat on permanent beds having 100 % crop residues (T3); Zero tillage rice-conventional tillage wheat without residues (T4); Zero tillage rice-zero tillage wheat on permanent bed (without residues) (T5); Zero tillage rice-Zero tillage wheat having 100% crop residues (T6); Direct seeded broadcasted rice-Zero tillage wheat (only rice residue in wheat cycle) (T7); Zero tillage rice with brown manuring-zero tillage wheat (without residues) (T8). The study aimed to assess how treatments affected yield, nutrient absorption, and the transformation of various pools of nitrogen, phosphorus, potassium and sulphur, as well as measure soil health in a rice-wheat system. The following are the findings of the present study which revealed that the adoption of zero tillage and crop residue amplified grain yield of rice by 3.91-15.49% although; treatment T8 showed the greatest improvement (by 15.49 percent) as compared to T1's standard procedures. While, in wheat, of zero tillage and residue retention practices increased the grain yield by 34.13- 63.94% over T1 and highest increment (by 63.94%) was established with T3. Treatments T6, T8, T3, T7, and T5 showed a significant increase in system yield by 33.12%, 32.46%, 31.78%, 22.64% and 21.96%, respectively over conventional practices. The nutrient uptake followed similar trend of yield with rice and wheat. The adoption of zero tillage and residue retention practices T3, T5, T6, T7 and T8 revealed higher total N, P, K, S uptake by rice crop by 38.39-26.00%, 10.25-26.64%, 11.05-31.29% and 10.04-37.70%, respectively over the conventional practice (T1). The total uptake of N, P, K and S by wheat crop was to the tune of 27.33-72.13%, 30.13-73.79%, 27.10-79.72% and 41.63-117.92% over conventional practices (T1) by T3, T4, T5, T6, T7 and T8, respectively. Similarly, total micronutrient uptake cations (Iron, manganese, copper and zinc) by rice crop were boosted with the involvement of zero tillage and residue retention to the tune of 11.12-34.83%, 12.73-37.56%, 9.91-41.77% and 10.04-37.71% over conventional practices for T3, T5, T6, T7 and T8, respectively. Likewise, the total uptake of iron, copper and zinc by wheat crop was to tune of 34.67%, 33.48%, 38.44% and 41.00%, respectively over conventional practices (T1). Different N-fractions in soil were ranked in order of dominance: Total N > Total hydrolysable-N > Non-hydrolysable-N > Hydrolysable ammonical-N > Exchangeable ammonical-N > Amino acid-N > Unidentified-N > Hexoseamine-N > Nitrate-N. The treatment ZTR-ZTW+ R showed the highest forms among most of the N fractions, along with ZTR-ZTW (B) + R and ZTR-ZTW (B) + R and ZTR+BM-ZTW being at par. The major pool of P in the soil was organic-P. Excluding Al-P and Fe-P, all the other forms of P was increased with zero tillage, residue management and brown manuring. The following was the average order of various fractions status of P: Organic-P > Ca-P > Mineral-P > Saloid-P > Fe-P > Al-P. The total-K ranged between 14800.2 mg kg-1 to 15643.0 mg kg-1 due to different treatments. Lattice-K contributed the major fraction of K in soil. Retaining residues on soil surface and zero tillage had increased the amount of all forms of K. The order of the availability of different K forms in the soil is as follows: Total-K > Lattice-K > Non-exchangeable-K > Exchangeable-K > Water soluble-K. The total-S varied from 225.27 to 294.43 mg kg-1 due to different treatments. Organically bound-S contributed the major fraction of S in soil. Retaining residues on soil surface and zero tillage had increased the amount of all form of S except residual-S. The availability of different S pools was in the order: total-S > organically bound-S > residual-S > inorganically bound-S > distilled water soluble-S > sulphate-S. The correlation coefficient study specified that all the fractions of N, P, K and S were in dynamic equilibrium showing positive significant relationship with the majority of plant and soil attributes. The pH and EC content at the commencement of the experiment in 2006 were higher as compared to values obtained under conservation agriculture plots. However, when conservation techniques were used, available macro and micronutrients were enhanced compared to their baseline data which were obtained before the trial began in 2006. Involvement of CA practices significantly altered the soil health parameters viz. soil physico-chemical and biological properties. After one cycle of rice-wheat, conservation agriculture increased the wet aggregate stability (%). The CA (ZTR-ZTW (B)+R, ZTR-ZTW(B)-R, ZTR-ZTW+R, DSR-ZTW+R.R and ZTR+BM-ZTW) practices recorded increase to the tune of 38.15%, 17.24%, 34.48%, 28.87% and 32.75%, respectively over the control. The CA practices increased the soil organic carbon with time as the increment in SOC (0- 15 cm soil depth) with conservation agriculture adoption (T2, T3, T4, T5, T6, T7 and T8) was by 16.37- 86.04% over conventional practices. The active carbon varied between 165.0 mg kg-1 in conventional plot to 373.3 mg kg−1 in ZTR-ZTW (B) +R. The treatment ZTR-ZTW (B) +R was significantly superior and at par with ZTR-ZTW+R (62.4 mg kg−1) and ZTR+BM-ZTW (61.6 mg kg−1). The magnitude of increase in active carbon was 4.36%, 15.57%, 46.66%, 95.81%, 97.87%, 106.06% and 126.24% over control. Soil respiration varied between 1.53 CO2 mg g−1soil in control plot to 1.88 CO2 mg g−1soil in ZTR-ZTW (B) +R. The magnitude of increase in soil respiration was 1.30%, 4.57%, 7.84%, 10.45%, 16.33%, 18.30% and 22.87% over control in treatments ZTR-CTW-R, PTR-ZTW, ZTR-ZTW(B)-R, DSR-ZTW+R.R, ZTR+BM-ZTW, ZTR-ZTW+R and ZTR-ZTW(B)+R, respectively. The magnitude of increase in ACE protein was 6.37%, 9.96%, 12.75%, 19.92%, 23.90%, 26.69% and 28.29 % over control in PTR-ZTW, ZTR-CTW-R, ZTR-ZTW(B)-R, DSR-ZTW+R.R, ZTR-ZTW+R, ZTR-ZTW(B)+R and ZTR+BM-ZTW, respectively. Hence, conservational agricultural system contributed to higher production of ACE protein. The ZT with residue retention was found to be superior over CT due to congenial crop-soil environment. Thus, long term effect of crop establishment with varying degrees of residue retention improved different pools of soil nitrogen, phosphorus, potassium and sulphur; soil health parameters and thereby, enhanced the soil health in the long run.EnglishThesis