DESIGN AND ANALYSIS OF EXPERIMENTS ON CROPPING SYSTEMS

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1 DESIGN AND ANALYSIS OF EXPERIMENTS ON CROPPING SYSTEMS Rajinder Kaur I.A.S.R.I., Library Avenue, New Delhi Experiments on cropping systems are ultimate solution to overcome the drawbacks of monocropping system or seasonal experiments and to exploit the soil intensively for food production in view of growing population at an alarming rate. The technique of crop intensification helps in increasing the yield per unit area per unit time. Continuous cropping, the substitute of single crop cultivation results in rapid decline in soil fertility and thus require a serious attention to efficient fertilizer use. Generally response to P and K manifests only if an experiment has been carried out for two, three or more years at a site, when the amounts easily available in the soil have been exhausted either due to increased plant growth or continuous application of nitrogen alone. Particularly, the FYM being a slow release source of nutrients its usefulness can be investigated in a crop sequence rather than for a single season individual crops. The results from one-season experiments are liable to be misleading if they are applied to the continuous cropping situation. As such results of the experiments carried out at the same site continuously over a number of years will provide more reliable and additional information of practical utility from the farmers point of view, who most often adopt on a permanent basis a cropping system suitable to their agro-environments. Therefore, fertilizer recommendations should be framed for a cropping system instead of a single crop because fertilizer recommendations for a single crop results sometimes in high and uneconomic use of fertilizer and do not consider the fact that fertilizer needs of a crop vary depending upon the characteristics of the preceding crop in the system due to residual effect of fertilizers applied to one crop to succeeding crop. To strengthen all aspects of research in the field of cropping systems, Project Directorate for Cropping Systems Research (PDCSR) was established in the seventh five-year plan which started functioning during April 1989 at Modipuram-Meerut and experiments were planned with the following objectives: (i) To identify profitable and emerging efficient cropping systems for different agroclimatic regions with special emphasis on oilseeds pulses and fodder crops. (ii) To develop integrated nutrient supply and management techniques with emphasis on locally available resources. (iii) (iv) To develop system based crop management practices. To develop system based crop management practices for maximizing yield in each ecosystem. At present PDCSR has a network of 37 on - station research centres which are functioning under collaborative agreement with all the SAUs in the country and spread over five major ecosystems viz. arid, semi arid, sub-humid, humid and coastal. The following type of experiments were conducted at different research centres:

2 i) Development of new cropping systems a. Identification of need based cropping systems for different agro-climatic regions. b. Comparative performance of different period bound rotations. c. Crop geometry and nutrient management for new intercropping systems. d. Long term studies on the relative efficiency of legume-cereal or cereal - legume rotations over cereal-cereal rotations. ii) Nutrient management in cropping systems a. Permanent plot experiment on integrated nutrient supply in cereal based crop sequences. b. Long range effect of continuous cropping and manuring on soil fertility and yield stability. c. Determining frequency of P application for judicious use of P fertilizers. d. Conservation of organic carbon in the soil to improve soil conditions. e. Monitoring secondary and micronutrients in intensive cropping systems. f. Crop residue management in rice-wheat system. g. Phosphorus management in rice-wheat system. iii) Development of system-based management practices a. Tillage and planting management in rice-wheat system. b. Tillage and planting management in rice-pulse/oilseed system. c. Minimum tillage for soyabean based rainfed double cropping system. d. Water management in rice-wheat system. e. Rotation of herbicides in rice rice sequence for the prevention of new biotypes of weeds. iv) Maximum yield research a. System based maximum yield research ii(a) and ii(b) are two long term experiments continuing since and respectively. Remaining experiments are of 4-6 years duration conducted on a fixed site with the same layout, same cropping system and same set of treatments. Design of experiments Generally the designs adopted were randomized block and split-plot designs. But other designs like split-split plot, strip plot, factorial RBD, 3 2 x2 factorial partially confounded with one control plot in each block, 4x2 2 balanced confounded and balanced incomplete block designs with different parameters like (9,12,4,3,1), (7,7,4,4,2), (6,10,5,3,2), (13,13,4,4,1) and (15,35,7,3,1) were also adopted. Treatments As per the objective of the experiments, treatments were used to be finalised for a cropping system which may not give the set of distinct treatments in each season but combinations of treatments in both the seasons gave a set of distinct treatments. Example 1: Experiment for developing integrated nutrient supply system in cereal based crop sequences was conducted with the following set of treatments 588

3 Kharif Rabi 1. Control Control 2. 50% RCF 50% RCF 3. 50% RCF 100% RCF 4. 75%RCF 75%RCF % RCF 100% RCF 6. 50% RCF +50% through FYM 100% RCF 7. 75% RCF + 25% through FYM 75% RCF 8. 50% RCF +50% through C.R. 100% RCF 9. 75% RCF + 25% through C.R. 75% RCF % RCF + 50% through GM 100% RCF % RCF + 25 % through GM 75% RCF 12. Farmer'practice Farmers practice RCF Recommended fertilizer; CR Crop Residues; GM Green Manure; Combinations of treatments in both the seasons gave 12 distinct treatments. Example 2: An experiment "Rotation of herbicides in rice-rice sequence for the prevention of new biotype of weeds " was conducted with the following set of treatments. Kharif Rabi 2,4-Dee Pendimethalin 2,4-Dee Pendimethalin + Hand + Hand Weeding once Weeding once Hand weeding twice Hand weeding twice Unweeded Unweeded For development of system based management techniques experiments were planned with such a treatment set up which used to be beneficial not only to a single crop but to the cropping system followed 589

4 Example 3: Tillage and planting management in rice-wheat cropping system Main plot treatments (in rice) Subplot treatments(in wheat) Transplanting rice after (i) conventional tillage (i) reduced puddling (50%) (ii) Reduced tillage (50%) (ii) normal puddling (iii) Zero tillage (iii) normal puddling after summer green (iv) Seedling after one harrowing followed manure crop by planting for this treatment set up layout has been prepared in kharif itself showing the main plots for Kharif and sub plots for rabi treatments and observations are recorded accordingly. By doing this, we have studied the residual effect of transplanting techniques adopted in kharif on wheat yield and tillage treatments applied for rabi crop on next rice crop. Example 4: This experiment was conducted at Palampur during and the results obtained for the 2 nd year are as under: Centre : Palampur Season : Kharif Crop / variety : Rice / RP-2421 Wheat / HPW-42 Recommended Dose NPK (Kg/ha) : Main Plot Treatment Grain Yield (Kg/ha) P 1 P 2 P 3 Mean P 1 P 2 P 3 Mean SubPlot Treatment T T T T Mean S.E. (CD 5%) of difference between a. two main plot means 137(336) 346(NS) b. two sub plot means 114(NS) 205(NS) c. two main plot at sub plot 234(NS) 673(NS) d. two sub plot at main plot 213(NS) 382(NS) Results: During Kharif, transplanting rice after reducing puddling and after normal puddling after summer green manure crop produced comparable rice grains and significantly superior to transplanted rice after normal puddling. The residual effect of tillage adopted in wheat was observed with conventional tillage plots giving maximum rice yield of 43.8 q/ha which was superior to all other tillage treatments. During rabi, the residual effect of transplanting in rice was observed with transplanting after normal 590

5 puddling after summer green manure crop giving maximum wheat yield of q/ha followed by transplanting after reduced puddling and normal puddling. The effect of tillage treatments on wheat yield was significant. Seeding after one harrowing followed by planking gave maximum yield (38.82 q/ha) which was comparable to conventional tillage (37.10q/ha) but after superior to reduced (33.14 q/ha) and zero (31.11 q/ha) tillage treatments. References Annual REports of All India Co-ordinated Research Project on Cropping Systems (ICAR), published by PDCSR, Modipuram, Meeraut (UP). 591