Cropping systems for drylands of the Indian arid zone. Central Arid Zone Research Institute, Jodhpur

Transcription

1 1 Annals of Arid Zone-19(4), , 1980 Cropping systems for drylands of the Indian arid zone.1. R. P. SINGH Central Arid Zone Research Institute, Jodhpur Cropping systems now in vogue in the Indian arid zone are not necessarily the most efficient with regard to productivity, moisture use, monetary returns and labour utilization potential. Single crop system involving a long fallow (October to June) is a rule rather than an exception. The principal dry land crops of this region are pearl millet, grain legumes (cluster beans, moth beans, mung beans), and oilseed crops (sesamum, etc.), besides fodder crops like pearl millet and sorghum. Mixed cropping as a means of insurance and risk distribution is quite common. There is a need to develop cropping systems which aims at maximising production in good and normal rainfall years, and stabilizing production in sub-normal rainfall years. The presentation that follows primarily deals with the experience gained by the author while working on the project, 'Cropping Systems for Drylands of Western Rajasthan'. Two themes are broadly presented and discussed: (1) Productivity, moisture use, monetary returns and labour utilization in different cropping systems, and (2) Water harvesting and run-off recycling for maximising and stabilizing production on drylands. The setting: The research work on cropping systems for drylands of Western 1<.ajasthan was initiated at the Central Arid Zon.e Research Institute, Jodhpur, in monsoon Single crop systems (Cenchrus ciliaris alone, pearl milletfallow, mung beans-fallow, cluster beansfallow, cas tor beans-fallow) were tried together with intercrop systems involving C. ciliaris and castor beans as the principal or base crops. Different inter-crop systems tried were: Cenchrus ciliaris+ mung beans, Cenchrus ciliaris+cluster beans, Cenchrus ciliaris+ moth beans, castor beans + moth beans for fodder. In the good rainfall year of 1975 with more than 500 mm rainfall and extended rainy season, double crop systems, viz. pearl millet followed by brassicas, and mung beans followed by mustard/sunflower/safflower, were tried. Of the 1.25 ha land earmarked for this study, 1.0 ha, divided into four equal strips of 0.25 ha was cropped, while the rest ha) was kept fallow and utilized for water harvesting and collection of run-off water in a pucca pond (173 m 3 ) provided on the catchment. The results presented in this paper relate to the large sized unreplicated plot strips of uniform soil characteristics. Characterisation of the environment: Soils are aeolian in origin, having loamy sand surface soil and sandy loam sub-soil. The infiltration rate (steady state) is quite high (5 cm/hr). The soil depth is about 100 cm, with a moisture storage capacity of about 130 to 135 mm. The clay, silt and coarse sand fractions in the soil profile increased with depth, while fine sand

2 438 : R. P. SINGH fraction decreased with depth. The ph, Ec (1 :2 mmms / cur), organic carbon (per cent), available P20s (kg/ha) and' available K 2 0 (kgjha), were 7.8, 0.12, 0.2, 18.8 and 212.0, respectively. The environment where the research on the present cropping systems was c~rried out falls in a region of low ramfall (366 mm), most of which (80 per cent) is received during the monsoon season (July to September). The me~n number of rainy days during the cropplllg season is 21 only. The data reported in this paper pertains to the years 1975, 1976, and 1977 which experienced 535, 549 and 316 mm of rainfall with 34, 26 and 21 rainy days, respectively. The rainfall ~istribution was quite favourable dunng 1975 and The 36th meteorological week in the years 1975 and 1976 received 173 and 187 -mm rainfall, which enabled a double.crop system to be adopted' on drylands. 1. Productivity of different cropping systems 1;1. Single q:op systems: Among the various single crop, systems tried, pearl millet-fallow proved to be the most remunerative, with an, average yield of 24S q/ha and gross monetary returns of Rs. 3,464/ha. Between cluster beans and mung beans, the former seemed to be more prolllising, in terms of productivity per unit area, although the latter proved mon; remunerative because of higher price of the produce. Castor beans, as an oilseed crop, showed promise, with good production potential (9.3 q/ha) and gross monetary returns (Rs. 2,465 /ha) Double crop systems: Double cropping on drylands of this region is not quite common. HoweveF, years having more than 500 mm rainfall with an extended rainy season favour double cropping. An analysis of 75 years of rainfall data (1901 to 1975) of Jodhpur revealed that 18 years were such which showed promise for double crop?ing on drylands. In the year four crops, viz. mustard (Brassica juncea), rape (Brassica campestris var. brown sarson), toria (Brassica campestris var. tori a ), and taramira (Eruca sativa) were sown on residual soil moisture after the field was vacated by pearl millet with a view to studying the comparative performance of each crop. Of these, mustard (T 59) gave the highest yield (9.5 q/ha), followed by toria (8.0 qjha), rape (5.1 q/ha) and taramira (7.6 q/ha). The field vacated by mung beans was put under mustard, sunflower and safflower and the respective yields were 7.1, 304 and 7.3 q/ha. From the above, it is clear that pearl milletmustard and mung beans-mustard are the most promising double crop systems for this area. In fact, between mung beans-mustard and mung beans-safflower double crop systems, there is nothing much to choose as both these systems exhibited the same pattern of productivity and gross monetary returns. Based on the mean values of three years (1975 though 1977) it is seen that pearl millet followed by mustard gave the highest total productivity (30.3 q/ha) and gross monetary returns (Rs 5,546 qjha). In the year 1976, mustard was sown on residual soil moisture after pearl' millet and mung.'beans: The yield level obtained was not satisfactory because of heavy incioence of aphids.

3 DRYLAND CROPPING SYSTEMS : Inter-cropping systems: Among the inter-cropping systems involving Cenchrus ciliaris as the principal crop, intercropping of mung beans in between two rows of Cenchrus ciliaris, tried in 1975 and 1977 showed promise of high monetary returns. In the year 1977, three annual grain legumes, viz. mung beans, cluster beans and moth beans were intercropped with Cenchrus ciliaris, the yield of the grain legumes obtained was of the order of 8.2, 11.5 and, 1.2 q/ha respectively, in addition to 70, 68 and 65 qlha of green forage, respectively. In case of castor, moth beans for fodder was sown in between two rows of castor, in 1976 and 1977, the mean yields of respective crops obtained being 9.2 and 39.9 q/ha. An interesting feature of the intercropping systems involving Cenchrus cuaris and castor beans as principal crops was that inter-cropping of the companion crop had no adverse effect on the yield of the principal crop and two together gave more remunerative returns than Cenchrus ci/iaris and castor beans alone. For example, the inter-cropping system of Cenchrus ciflaris + mung beans gave gross returns of Rs 2,992/- per ha as compared to Rs 512/ -of Cenchrus cilia-!'is alone. Additional returns of Rs 572/- per ha were obtained by inter-cropping moth beans with castor beans over the single cropping of castor beans alone. The Land Equivalent Ratio (LER) in respect of each inter-cropping system tried were worked out (Table -1). It is seen that total LER was more than unity in case of C. ciliaris grown in association with mung beans ( 1.84), cluster beans (1.73) and moth beans (1.57), suggesting thereby that better utilization of land and higher total productivity could be obtained through judicious inter-cropping systems. Table I. Productivity and. Land Equivalent Ratio (LER) of different crops grown in single and intercroppingsystems (monsoon 1977) Crop Yield (kgfha) LER 1. Mung beans 1, Cluster beans 1, Moth beans ' Cenchrus ciliaris Castor 520 Inter-cropping I. C. ciliaris mung beans Total LER C. ciliaris J.OI cluster beans 1, Total LER C. ciliaris moth beans 'Total LER Castor moth beans (F) 344 An investigation on the inter-cropping systems for drylands, with sunflower as the principal crop, was carried out from 1973 to In general, the productivity of the inter-cropping 'systems was found to be 74 per cent higher than the pure cropping of sunflowers. Higher monetary returns were obtained from sunflower + cowpeas and sunflower + green gram inter-cropping systems over the other systems tried (Singh and Singh, 1977 ).

4 440 : R. p.. SINGH In a separate study on cropping intensity carried out by the author, it was revealed that castor-fallow was a more remunerative single crop system than fallow-mustard crop system. This suggests that efficient utilization of monsoon rains i5>ensured by growing a crop in the monsoon season itself rather than leaving the land fallow and taking a chance with conserved moisture. Among the double crop systems, mung beans followed by mustard and pearl millet followed by mustard systems were equally promising. Pearl millet grown for fodder followed by mustard was as remunerative as pearl millet grown for grains followed by mustard. Of the fodder crop sequences, the best sequence with regard to productivity and gross returns was cluster beans for fodder followed by castor beans. Cropping systems like these seem to impart greater stability to crop production on drylands Moisture use as affected by cropping systems: Studies on moisture use indicated that total moisture use by different crops in 1977 ranged between 245 mm in the case of pearl millet to 261 mm in the case of mung beans and cluster beans. The highest moisture use efficiency was e"hibited by pearl millet, followed by cluster beans, mung beans, and castor beans (Table 2). A comparative study of moisture use by pearl millet and mung beans grown in the conventional and paried row systems of planting in monsoon 1977 revealed that the paired row system of planting showed higher moisture use at the seedling stage. In the subsequent growth stages, however, the paired row system proved to be more efficient than the conventional system of planting pearl millet and mung beans. Results of replicated trials carried out during monsoon seasons during 1975 and 1976 revealed that the paired systems of planting pearl millet proved to be more efficient with regard to utilization of moil/- ture from deeper layers of the soil profile than the conventional system, besides exhibiting higher moisture use efficiency (Singh et ai., 1978). Crop canopy in the paired row system absorbed 2.0 times more radiant energy than the conventional system of planting (Ramakrishna et ai., 1977). Table 2. Yield, total moisture use (ET) and moisture use efficiency of dryland crops, Jodhpur (monsoon 1977) Crop Pearl millet Mung beans Cluster Castor beans beans Grain yield (q/ha) Total moisture use (ET) (mm) Moisture efficiency (kg/hat mm) Moisture use data as influenced by iuter-cropping systems indicate that the inter-cropping systems per se utilise more moisture than sole crops of Cenchrus ciliaris and castor beans. Grass + cluster beans showed higher total moisture use, followed by grass + mung beans, grass + moth beans and grass alone. Between castor alone and castor + moth beans inter-cropping system, the latter showed little higher total moisture use than the former. The moisture use in castor + moth beans system was particularly high during the period from 13 August to 8

5 DRYLAND CROPPING-SYSTEMS:' 441 September. In the studies carried out earlier on systems of planting mung beans (1975 and 1976), it was revealed that the consumptive use was not materially affected by growing a companion crop of pearl millet in the inters paces of mung beans over that of the pure crop of mung beans. The moisture use efficiency of the -inter-cropping systems was almost double than that of the sole crop systems (Singh et al., 1977) Economic evaluation of the cropping systems: Based on the mean productivity of 3 years (1975 to 1977), economic evaluation of different cropping systems was carried out. Of the various cropping systems tried, the highest returns (Rs 4.53) per rupee invested were obtained from the double crop system of pearl millet-mustard, followed by Cenchrus ciliaris + guar beans (Rs 3.67). Among the single crop systems, pearl millet-fallow gave the highest returns (Rs 2.76), followed by mung beansfallow, castor beans-fallow and cluster beans-fallow cropping systems: C. ciliaris gave the lowest returns per rupee invested (Table 3). The cost of production per hectare in the double crop systems involving pearl millet and mung beans was almost twice as much as the single crop systems of the respective crops. This suggests that dryland farmers with favourable monetary resources could go in for double cropping Table _3. Economic evaluation of cropping system Cropping system Total productivity (q/ha) Grain Fodder Cost of production (Rs/ha) Net profit (Rs/ha) Returns per year per rupee invested (Rs) Single cropping systems 1. Bajra-Fallow Guar-Fallow Mung-Fallow Castor-Fallow C. ci/iaris } Double cropping systems 1. Blljra-Raya Mung-Raya Mung-Safllower Inter-cropping systems 1. C. ciliaris + Mung (G) C. ciliaris + Guar( G) C.Ci/ iaris + Moth(G) L2 4. Castor + Moth (F) L

6 442 R. P. SINGH in years of favourable rainfall distribution with extended rainy season, so as to obtain higher returns on investment Cropping systems and employment potential: Round the year gainful provision of employment is possibly one of the major consideration for evolving any cropping system.. In a typical year, it has been estimated that dryland farm families remain unemployed for almost 2/3rd of the time. Change in crops and cropping patterns is one such way of generating additional employment. The employment potential pltr hectare was around 70 mandays ia case of mung beans and cluster beans, and 84 days in the case of direct seeded pearl millet. By replacing mung beans with castor beans, and the practice of direct seeding of pearl millet with transplanting in the event of delayed onset of monsoon, additional employment potential of the order of 25 and 8 labour man days per hectare could be created. By resorting to the double crop system of pearl millet followed by mustard in favourable rainfall years, the employment potential per hectare of 84 mandays in the single crop system of pearl millet could be increased to 176 mandays per hectare. By inter-cropping annual grain legumes (mung beans, cluster beans or moth beans) in the perennial grasses like Cenchrus ciliaris, additional employment potential to the extent of 20 mandays per hectare could be achieved over the sole cropping of C. ciliaris (59 mandays). With the adoption of improved cropping systems on drylands, more efficient utilization of machinery and equipment (hrsl ha) could be obtained, besides generating additional employment potential. The change-over from single crop to double crop system not only increases the employment potential and machinery utilization, but causes a most welcome increase in productivity. For example, the productivity of 0.8 tonsjha obtained in the mung-fallow system increased to 1.6 tons Iha in the case of mung beans-safflower cropping system. It can thus be inferred that the new double and intercropping systems establish the complementary of labour and capital productivity. Any cropping which meets the requirement of releasing these two cruci~i inputs from the orbit of competitiveness is also desirable for its widespread acceptability Water harvesting and run-off recycling: Arid regions are characterised by insufficient and uneven rainfall distribution. Occasional heavy showers producij1gsizeable run-off are, however, not uncommon. Recent experience has shown that the rainfall received in the arid zone, although insufficient to meet the ET demands of the environment has an intensity which can provide sizeable run-off on a few rainfall events, thus making water harvesting a distinct possibility in the arid zone. Annual water harvest effici"mcies vary from year to year depending on the frequency and intensity of rainfall, Rain water received over a bare catchment (0.25 ha) was harvested and stored in a pucca pond (173 m 3 ) during 1976 and 1977 monsoon seasons. Observations on run-off recorded in both the seasons indicated that run-off of the order of 15.8 to 26.6 per cent of the total rainfall could be harvested. In the monsoon cropping season of 1977, the run-off water stored in the pond was recycled for providing a supplemental irrigation (6.1 em) to the direct seeded and transplanted pearl millet, 39

7 DRYLAND CROPPING SYSTEMS 443 days after seeding/transplanting. The remaining water in the pond was used for a supplemental irrigation (5.2 cm) to castor beans, 44 days after sowing. As a result of supplemental irrigation, the increase in yield in pearl millet and castor beans was of the order of 7.2 and 10.2 per cent, respectively. The yield increase was only marginal in case of pearl millet, because rains of the order of 35 mm were received subsequent to supplemental irrigation. In the winter season of , a presowing irrigation (5.3 cm) was applied on 11 October 1976, with a view to taking a crop of mustard after pearl millet. Mustard was sown on 13 October. A supplemental irrigation (4.4 cm) was given on 20 December to a part of the area, in addition to one pre-sowing irrigation. The results indicate that by giving one pre-sowing irrigation, the yields of mustard could be pushed up to 163 per cent over no irrigation and the same could further be pushed up to 525 per cent by providing one supplemental irrigation in addition to one pre-sowing irrigation. These results suggest the importance of run-off recycling in stabilising and maximising crop production on drylands. ACKNOWLEDGEMENTS My grateful thanks are due to Dr. H. S. Mann, Director, Central Arid Zone Research Institute, Jodhpur, for providing necessary facilities and giving useful suggestions during the course of this investigation. Shri Bal Ram, Research Fellow (Agricultural Economics) assisted me in the economic evaluation of the cropping systems. Shri Ramu Ram, Fieldman, spared no efforts in the field execution of the project. My grateful thanks are due to both of them. REFERENCES Ramakrishna, Y. S., Singh, R. P. and Singh, K. C Influence of systems of planting pearl millet on crop micro-climate. Agricultural Meteorology (Communicated). Singh, K. C. and Singh, R. P Inter-cropping of annual grain legumes with sunflower. Indian I. agric. Sci. 47 (11): Singh, R. P., Singh, K. C. and Ramakrishna, Y. S Studies on systems of planting dryland crops. I. Pearl millet. Indian I. agric. Scl. 48(3) (Accepted).