Promising Chickpea based Cropping Systems for Vertisols of Andhra Pradesh

Now in India farmers concentrate mainly on monocropping system which is subjected to high degree of income and can decrease system productivity, reduction in profitability and declining in soil health. Continuous use of chemical fertilizers in intensive cropping system leads to imbalance of nutrients in soil, which has adverse effect on soil health and also on crop yields (Hashim et al., 2015). Inclusion of legumes and cereals in cropping system have advantage beyond N addition, recycling from soil layers, minimizing soil compaction, protecting soil from erosion, increasing soil organic matter through root biomass and leaf fall and minimizing the harmful allopathic effects (Jain et al., 2015).

In vertisols of scarce rainfall zone of Andhra Pradesh with unimodel distribution of rainfall mainly during kharif season, chickpea is grown as a rabi crop based on residual soil moisture. The promising cropping system over the years in this area is fallow- chickpea or cereal-chickpea, particularly with maize/foxtail millet-chickpea cropping system. From point of view of biological value and protein efficiency, pulse-chickpea cropping system provides better nutritional standards, sustain yields and soil fertility

The chickpea area in Andhra Pradesh under double cropping system is increasing recently due to higher yields and profits within short crop growing period by exploiting residual moisture. Since very little scope exists for horizontal growth the alternative seems by achieving vertical growth through increasing its productivity level. Under double cropping system, preceiding crop residues can incorporate to sustain the soil moisture which is the key factor to improve soil moisture content and organic carbon content of the soil as chickpea is mostly grown in residual moisture condition which decides the yields and returns.

Field experiments were carried out for two consecutive kharif and rabi seasons for the year 2018-19 and 2019-20 at R.A.R.S. Farm, Nandyal, Andhra Pradesh. The treatments comprised of three crop residue incorporations viz., foxtail millet, (C₁) greengram(C₂) and fallow(C₃) as main plot treatments and four times of sowing viz. October 2^nd FN (D₁), November 1^st FN (D₂), November 2^nd FN (D₃) and December 1^st FN (D₄) as sub plot treatments and three irrigation schedules as sub- sub plots with irrigation at pre-flowering stage (I1), irrigation at pod development stage (I2) and irrigation at pre-flowering and pod development stage (I3) During kharif season, foxtail millet and greengram crops were raised as bulk crops in respective main plots and crop residues were incorporated after harvest of economic parts viz., panicles of foxtail millet and pods of greengram. Experimental design was split-split plot, with three replications.

The site was situated at an altitude of 216 m above mean sea level at 15º29'19" N latitude and 78° 29'11² E longitude, mostly under rainfed conditions, categorized in the scarce rainfall agro-climatic zone of Andhra Pradesh. The meteorological data of maximum and minimum temperature, rainfall, number of rainy days, morning and evening relative humidity and wind speed were recorded from meteorological observatory, Regional Agricultural Research Station, Nandyal near the experimental site, during the period of crop growth. Soil of the site was medium in fertility and slightly saline in reaction having pH 8.42, electrical conductivity 0.24 dSm^-1, organic carbon 0.32% with available nitrogen, phosphorus and potassium 143, 53 and 451 kg/ha, respectively. Sowing of seeds was done in rows, 30 cm apart with 10 cm between plants. An amount of 20 kg nitrogen  and 50 kg P₂O₅ per hectare was  applied through urea and  SSP as basal. Sowing was done in four intervals as D1 on October 2nd fortnight, D₂ on November 1st fortnight, D3 on November 2nd fortnight, D4 on  December 1st fortnight, in respective treatment plots. Healthy and matured seeds of desi chickpea variety NBeG-3 having high germination percentage were used for sowing. Seed rate @ 50 kg ha^-1 was adopted and  sown in the open furrows made with the help of hand hoe. The seeds were dropped to a depth of 5 cm and covered thoroughly. System productivity indicators, land use efficiency, production efficiency,  sustainable yield index equivalent yields and economics were calculated based on standard formulas:
 
Land use efficiency
 
Land use efficiency of cropping system was calculated by using the following formula and expressed in percentage.

 

 Production efficiency
 
Production efficiency of cropping system was calculated by using the following formula and expressed in kg ha^-1 day^-1) based on chickpea equivalence yields.
 

  
 Sustainable yield index
 
The sustainable yield index for foxtail millet / greengram – chickpea cropping system was worked out by the formula given by Tomar and Tiwari (1990) based on chickpea equivalence yields.
 

 

 
 Equivalent yields and economics
 
The seed yield of the kharif crops was converted in to chickpea equivalents on the basis of price of seed of kharif crops involved in the cropping system.

The total cost of cultivation of double cropping system (ha^-1) was calculated for each treatment on the basis of input cost of both the seasons. Gross returns (ha-1) was computed by considering the prevailing market price of the outputs. Net return (ha^-1) were arrived by deducting the cost of cultivation from gross returns of corresponding cropping system. Cost benefit ratio was worked out for each system. 

Cropping system equivalent yields and economics
 
System productivity was estimated by converting foxtail millet and green gram yields into to chickpea equivalent yields and presented in Table 1 and outline indicates that foxtail millet - chickpea cropping system recorded higher chickpea equivalent yields, during both years of investigation followed by greengram - chickpea cropping system. Fallow - chickpea cropping system recorded lower values of chickpea equivalent yields in both years of study.



Cropping system cost of cultivation, gross and net returns and benefit cost ratio was calculated for all treatments for both years of study and presented in Fig 1 and 2). Gross and net returns were highest with foxtail millet- chickpea cropping system followed by greengram - chickpea cropping system. Minimum returns were obtained when fallow-chickpea system adopted.



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Under rainfed condition cultivation of foxtail millet / greengram in kharif season and incorporation of their residues before chickpea sowing effect on productivity and profitability of cropping system instead of fallow chickpea in vertisols. The same line of results was reported by Amgain et al., (2013).
 
Land use efficiency (LUE) (%)
 
Land use efficiency (%) of different chickpea based cropping systems under study was calculated and mean values were shown in Table 2. The data indicated that both foxtail millet -chickpea and greengram-chickpea cropping system increased the LUE by 20-25 per cent over fallow- chickpea cropping system in all four times of sowing. Hence, under rainfed vertisols foxtail millet-chickpea (46%) and greengram -chickpea (45.5%) was found suitable cropping system with high land use efficiency. similar line of results were reported by Dudhra et al., (2002).


 
Production efficiency
 
Production efficiency of three chickpea based cropping systems under different time of sowing were worked out and presented in Table 1. The data indicated that greengram - chickpea cropping system recorded high production use efficiency (48 and 69 kg ha^-1 in 2018-19 and 2019-20 respectively) followed by foxtail millet-chickpea (43 and 61 kg ha^-1 in 2018-19 and 2019-20 respectively) cropping system during both years of study. Fallow-chickpea cropping system recorded lower values in all four rabi chickpea sowing time.

These results indicated that greengram - chickpea and foxtail millet - chickpea were more productive systems under double cropping systems in vertisols of Andhra Pradesh. Pacharne et al., (2018) also reported that groundnut- onion cropping system recorded significantly maximum total productivity, production use efficiency, economic efficiency and maximum monetary returns when compared with groundnut- wheat/ groundnut- chickpea cropping system.
 
Sustainable yield index
 
The sustainable yield index values calculated for different treatments of foxtail millet / greengram-chickpea cropping system clearly showed the yield sustainability with crop residue incorporations and time of sowing of chickpea crop (Table 1).

The sustainable yield index values were higher during second year of study due to adequate rains, which helped in better decomposition of incorporated residues. By the end of the year of experimentation, greengram-chickpea cropping system showed higher values of SYI, due to higher organic carbon and added biological nitrogen. The lower SYI values were with fallow-chickpea cropping system, due to single season yields.
 
Soil carbon sequestration
 
Data on soil carbon content at different crop growth stages were calculated and shown in Table 3. After crop residue incorporation, when the sowing of rabi chickpea delayed from October to December, the soil organic carbon pool increased, however, the chickpea seed yield was not proportional to soil organic pool due to crop weather relations.



The soil organic content during the crop period of chickpea indicated that crop residues incorporation treatments significantly influenced the soil carbon sequestration only during rabi 2019-20, but not by time of sowing and irrigation treatments. Maximum soil carbon content was recorded with foxtail millet crop residue incorporation 7.19 (t ha^-1) and 9.93 t ha^-1 at 60 DAS and at harvest stages, respectively and on par with greengram crop residue incorporation values of 6.93 t ha^-1 and 9.18 t ha^-1. Significantly lower values were recorded with fallow- chickpea treatment.

Application of crop residues for two consecutive years improved the soil carbon content and showed positive response on chickpea crop growth and yield. This shows that crop residue incorporation technique is an important synergistic cultural practice to promote the way to mitigate the increased carbon content of the environment. Varalakshmi et al., (2005) also reported higher organic carbon content in groundnut- wheat cropping system.

In a nutshell, by the end of the experiment, greengram - chickpea cropping system had greater SYI values than foxtail millet-chickpea cropping system, owing to higher organic carbon and added biological nitrogen. Due to single-season yields, the fallow - chickpea cropping system had lower SYI values. Gross and net returns, as well as the B:C ratio, were higher with the foxtail millet-chickpea cropping system than with the greengram-chickpea cropping system on an equivalent yield basis. When using a fallow-chickpea system, the lowest returns were obtained. In the rainfed vertisols of Andhra Pradesh, double cropping systems combined with crop residue incorporation techniques have proven to be a crucial synergistic cultural practice and ideal productive cropping systems in light of changing climate.