Profitability of Rice based Cropping System by Sequencing Vegetable Cowpea under Various Establishment Techniques in Periyar-Vaigai Command

Rice is a predominant crop of Asian agriculture, and it has tremendous importance as it constitutes the major diet and serves as the main source of energy. It accounts for about 50% of the annual per capita calorie intake.

Predominant rice-producing regions in India are canal irrigated. The rice-fallow-rice system is a major cropping system in a canal command area. The Periyar-Vaigai command in Tamil Nadu provides water for a cultivated area of 80,000 ha, with a monsoon-dependent predominant rice-based cropping system, along with an average annual rainfall of 856 mm, distributed with high intensity (GOI, 2013).

Drought and crop failures are common phenomena during the post-rainy season due to high-intensity rainfall during Rabi (October-November). The soils become wet, reducing their workability. In canal-irrigated areas, the water delivery schedule does not always match the demand. Variations in the availability of irrigation water, coupled with the random nature of irrigation water supply, have created an imbalance in rice-based systems.

Mono-cropping of rice leads to:

• Declining yield
• Low land utilization efficiency
• Low system productivity
• Deterioration of soil fertility and health due to multiple nutrient deficiencies
• Declining factor productivity

Therefore, diversification is needed to identify suitable crop(s) for the dry period during summer. The only viable option is the cultivation of pulse-cum-vegetables during the dry period to achieve higher productivity and profitability. However, the scientific evidence and comparative assessment of stable systems incorporating non-rice crops remain limited.

Diversification has several benefits:

• Fulfills basic needs for cereals and vegetables
• Enhances farm income
• Withstands weather variations
• Conserves natural resources
• Creates employment opportunities
• Reduces risk

Hence, intensification of rice-based systems is crucial to increasing productivity and maintaining sustainability. These options have not been systematically studied under the Periyar-Vaigai command. Given these circumstances, the green manure-rice-legume cum commercial cropping system offers great potential to overcome risks and effectively utilize resources.

A field experiment was carried out to evaluate the crop establishment techniques and various crop geometries on the profitability of the rice-vegetable cowpea cropping system during the Rabi (October-January) season of 2013-14 and the summer (February-May) season of 2014 in the Department of Farm Management, Agricultural College and Research Institute, Madurai.

The experimental site is located in the southern agro-climatic zone of Tamil Nadu at 9° 54’ N latitude and 78° 54’ E longitude, with an elevation of 147 m above MSL. The quantity of precipitation received through rainfall during the period of sequential cropping (October 2013-May 2014) was 240.6 mm, distributed over 18 rainy days.

The field experiment was laid out in a strip plot design, and the treatments were replicated thrice. The soil of the experimental field was clay loam in texture, belonging to Typic Ustropept. The nutrient status was low in available nitrogen, medium in available phosphorus, and high in available potassium.

Treatment Combinations

The treatment combinations included four crop establishment techniques:

• Puddled transplanting (E1)
• Unpuddled transplanting (E2)
• Puddled direct seeding (E3)
• Unpuddled direct seeding (E4)

Additionally, four crop geometries were studied:

• 30 cm × 20 cm (S1)
• 20 cm × 10 cm (S2)
• 25 cm × 25 cm (S3)
• 30 cm × 30 cm (S4)

The rice variety ADT 39 was chosen for the study. Rice seedlings (18 days old) were transplanted in both puddled and unpuddled soil conditions, following the prescribed crop geometry for each treatment (E1 and E2).

For puddled and unpuddled direct-seeded conditions, seeds were treated with Azospirillum at 600 g kg⁻¹ as a pre-sowing seed treatment. 2-3 seeds were then placed manually according to the spacing treatment (E3 and E4).

Irrigation and Management Practices

• Puddled Transplanting

  • The experimental plots were irrigated to a depth of 2 cm uniformly in all treatments until the appearance of hairline cracks, up to the panicle initiation stage.
  • After panicle initiation, plots were irrigated with 5 cm depth of water upon the disappearance of ponded water.
  • Irrigation was stopped 15 days prior to harvest.

• Puddled Direct Seeding

  • Before sowing, the field was drained to maintain saturation for easy sowing and uniform seedling establishment.
  • A thin film of water was maintained during sowing.
  • For the next 8-15 days, irrigation and drainage were alternated to ensure aeration and adequate moisture for seed germination and seedling establishment.
  • Thereafter, the plots were irrigated up to soil saturation, uniformly across all treatments, until the panicle initiation stage.
  • After panicle initiation, plots were irrigated with 5 cm depth of water upon the disappearance of ponded water.
  • Irrigation was stopped 15 days prior to harvest.

• Unpuddled Transplanting

  • Before transplanting, the soil was saturated, and a thin film of water was maintained during transplanting.
  • For the next 8-15 days, irrigation and drainage were alternated to ensure aeration and adequate moisture for seedling establishment.
  • Subsequent irrigation was scheduled to saturate the soil at critical crop growth stages.

• Unpuddled Direct Seeding

  • After sowing, life-saving irrigation was applied on the 3rd day after transplanting (DAT) to support seedling establishment.
  • Further irrigation was applied at critical crop water requirement stages.

Vegetable Cowpea Cultivation

• The succeeding vegetable cowpea was grown without disturbing the layout of the rice crop.
• Vegetable cowpea seeds were dibbled between rice stubbles, following the spacing treatment scheduled for rice.
• After life-saving irrigation, plots were irrigated at ten-day intervals.
• Five plants per plot were randomly selected and labeled for recording observations across all three replications.

Yield Parameters

Rice

• Grain Yield

  • Grains from each net plot were harvested, cleaned, sun-dried, and weighed.
  • The yield was adjusted to 14% moisture content and recorded in kg ha⁻¹.

• Straw Yield

  • The straw obtained from each net plot area was sun-dried and weighed.
  • The straw yield was expressed in kg ha⁻¹.

Vegetable Cowpea

• Vegetable Yield

  • Pods were picked from each treatment plot and quantified.
  • The total vegetable yield was assessed as the sum of three harvests.

• Haulm Yield

  • After three harvests, the plant weight from the net plot was recorded and expressed in kg ha⁻¹.

System Productivity for Cropping System

• The total quantity of produce obtained from each crop was converted into rice grain equivalent yield by working out the ratio between total economic output from each crop and the cost of rice/kg.

Economic Analysis

• Cost of Cultivation and Gross Return

  • These were worked out based on the prevailing input cost and the market price of the grain at the time of the experiment (as suggested by Bhandari, 1993).

• Net Income

  • Net income was calculated by deducting the cost of cultivation from the gross return.

• Benefit-Cost Ratio (BCR)

  • The BCR was also calculated to evaluate the economic feasibility of the treatments.

Effect on Grain and Straw Yield of Rice

Square planting of 25 × 25 cm produced 5148 kg ha⁻¹; however, it was comparable with 30 × 30 cm (5010 kg ha⁻¹) and 30 × 20 cm (5288 kg ha⁻¹). Lower grain yield of 4997 kg ha⁻¹ was obtained in the spacing of 20 × 10 cm. A similar trend was noticed in straw yield as well.

Results indicated that wider spacing had linearly increased the performance of individual plants. The plants grown with wider spacing had more land area around them to draw nutrients and received more solar radiation, enhancing the photosynthetic process and leading to better individual plant performance.

The reason for the deviation from this linearity in the case of grain yield per plot is that yield not only depends on the performance of an individual plant but also on the total number of plants per plot and the yield-contributing parameters within the plant.

A higher grain yield of 6963 kg ha⁻¹ and straw yield of 9299 kg ha⁻¹ were obtained under the combination of puddled transplanting with 25 × 25 cm spacing (Oteng et al., 2013).

Table 1. Crop establishment techniques and crop geometries on grain yield and straw yield of rice

Table 2. Crop establishment techniques and crop geometries of rice on vegetable and halum yield of
succeeding vegetable cowpea

able 3. Crop establishment techniques and crop geometries on system productivity and profitability of
Dhaincha - Rice -Vegetable cowpea cropping system

System Profitability

Dhaincha-Rice-Vegetable Cowpea System

Profitability was determined through cost of cultivation, gross and net returns, B:C ratio, and per-day return. Methods of cultivation for rice and crop geometries had a notable influence on system productivity.

Cost of Cultivation

Establishment techniques and crop geometries greatly influenced the cost of production of the cropping system. Puddling and transplanting techniques incurred higher costs than dry ploughing and direct seeding. In the case of various crop geometries with different plant densities, seed cost accounted for the difference in the total cost of production.

Among the various establishment and crop geometry combinations, puddled transplanting with 25 cm × 25 cm utilized a higher cost (₹63,500), whereas the lower cost (₹50,344) was spent for 30 cm × 20 cm along with unpuddled direct seeding.

Gross and Net Return, Per Day Return, and B:C Ratio

System productivity directly determined the gross and net income from the system at the end of the cycle. Total and net income was higher (₹1,28,530 and ₹77,930) in unpuddled direct seeding with 30 × 30 cm due to high system productivity, whereas the lowest (₹76,890 and ₹14,037) was recorded in 20 × 10 cm along with transplanting in unpuddled soil.

The same combinations recorded a similar trend in per-day income (₹643 and ₹384) and benefit per rupee invested (2.54 and 1.22).

Among the various treatment combinations, wider spacing of 30 × 30 cm and unpuddled direct seeding (E₄S₄) had a higher profit margin with lower production cost. In general, production cost was higher in transplanting methods than in direct seeding due to labour costs for land preparation and crop management. Additionally, puddling incurred a higher cost than dry ploughing. The opposite trend was observed for system profitability.

In the case of crop geometries, wider spacing obtained higher profit than closer spacing. The lowest system yield and profit were recorded in unpuddled transplanting with closer spacing (20 × 10 cm) (E₃S₂).

From the experimental results, it can be concluded that the inclusion of a legume cum vegetable crop like vegetable cowpea in a rice system, especially in the Periyar-Vaigai canal command area (double crop wetland), will be remunerative with unpuddled direct seeding of rice fallow vegetable cowpea.