Maize equivalent yield (MEY)
The result revealed that the average yield of sole crops
i.e. maize, soybean, groundnut and cowpea were 11.5 t ha
-1 (green cob), 2.0 t ha
-1, 2.25 t ha
-1 and 2.2 t ha
-1 (as vegetables) respectively (Table 1). The yields of respective crops were converted into maize equivalent yield (MEY). The result revealed that the green cob yield of sole maize was found to be highest (7.1 t ha
-1) which was followed by groundnut (6.9 t ha
-1), cowpea (5.0 t ha
-1) and soybean (4.0 t ha
-1).
However, among the different maize based intercropping cropping system (additive series) the highest maize equivalent (10.2 t ha
-1) was recorded in maize + groundnut cropping system (1:1) which was followed by maize + soybean (1:1) 8.9 t ha
-1 and maize + cowpea (1:1) 8.4 t ha
-1. This result was in conformity with the experiment conducted at the Indian Agric. Research Institute revealed a significant dry matter accumulation of maize and groundnut intercropped in 1:1 row ratio arrangement
(Aravindkumar et al., 2004). On the other hand, among the different strip cropping (intercropping) system, maize + groundnut cropping system (4:4) recorded 7.4 t ha
-1 which was followed by maize + cowpea (4:4) 7.3 t ha
-1 and maize + soybean (4:4) 7.2 t ha
-1.
The system production efficiency were also studied under different cropping system and the result reveals that the highest system production efficiency was found in maize + groundnut (1:1) (additive series) cropping system (27.95 kg ha
-1 day
-1) which was followed by maize + soybean (1:1) cropping system (24.38 kg ha
-1 day
-1). On the other hand, among the strip cropping system, maize + groundnut (4:4) recorded the highest system production efficiency (20.27 kg ha
-1 day
-1) as compared to other strip cropping system. The advantage of intercropping with more efficient utilization of all available resources and increased productivity compared with each sole crop of the mixture
(Mucheru-Muna et al., 2009).
Soil fertility status
The soil fertility status for organic carbon, nitrogen, phosphorous and potassium were studied after harvest of the crops and the result revealed that growing of sole soybean, groundnut and cowpea or inclusion of the said crops in maize based cropping system enhanced the fertility status of soil (Table 2). The highest SMBC and organic carbon (66.20±5.65 mg g
-1; 1.26±0.09%) were recorded with the cultivation of cowpea as a sole or intercrop, which was found to be significantly superior over other sole and intercropping system under the study followed by soybean (46.35±3.96 mg g
-1; 1.23±0.09%). Among the intercropping system maize + cowpea (1:1) recorded the highest SMBC and organic carbon (31.85±2.72 mg g
-1; 1.07±0.07%). The same trend of results were also recorded in strip (intercropping) cropping of maize + cowpea (4:4) which was found to be significantly superior over maize + groundnut (4:4). This was in conformity with a study by
Vesterager et al., (2008). The available soil nitrogen, P
2O
5 and K
2O were also found to be the highest after harvest of the crops where cowpea was cultivated as sole, intercrop or strip cropping system. The highest N, P
2O
5 and K
2O recorded for cowpea when grown as sole crop was 414.48±17.98 kg ha
-1, 21.30±1.54 kg ha
-1 and 407.68±23.54 kg ha
-1 respectively. In the intercropping system (additive series), maize + cowpea (1:1) recorded the highest N, P
2O
5 and K
2O kg ha
-1 as 350.71±15.21 kg ha
-1, 18.89±1.37 kg ha
-1 and 394.24±22.76 kg ha
-1 respectively which was found to significantly superior over the other intercropping system. On the other hand, among the entire strip cropping system, maize + cowpea (4:4) recorded the highest soil available N, P
2O
5 and K
2O kg ha
-1 as compared to other strip cropping system under the study. This was in conformity with the study by Vesterager
et al. (2008). They found that maize and cowpea intercropping was beneficial on nitrogen poor soil. Maize and cowpea intercropping increases the amount of nitrogen, phosphorus and potassium contents associated to monocrop of maize
(Dahmardeh et al., 2010). Degraded and infertile soils were realized as a result of continuous monocropping and insufficient organic matter reprocessing coupled with occurrence of rainfall variability marked by common dry spells accounting for low crop yield
(Amos et al., 2012). Adeleke and Haruna (2012) also in their findings revealed an increase in total nitrogen after cropping any of the four legumes (soybean, cowpea, lablab and groundnut) and when the land was left fallow.
Economics
The economics of different cropping systems for cost of cultivation, gross return, net return, return per ₹ invested, cost benefit ratio and system profitability were also studied (Table 3). The result revealed that among different sole crops maize was found to be the most profitable crop having cost of cultivation (₹ 21.64 × 10
3), gross return (₹ 93.16 × 10
3), net return (₹ 71.52 ×10
3), return per ₹ invested (4.31), B:C ratio (3.31) and system profitability (₹ 255.23 ha
-1 day
‑1) which was closely followed by groundnut. Among the intercropping system (additive series), maize + groundnut (1:1) was found to be the most profitable with cost of cultivation (₹ 29.64 × 10
3), gross return (133.12 × 10
3), net return (103.48 × 10
3), return per ₹ invested (4.49), B:C ratio (3.49) and system profitability (₹ 364.71 ha
-1 day
-1). On the other hand, among the strip cropping system maize + cowpea (4:4) was recorded to be the most profitable with cost of cultivation (₹ 20.17 × 10
3), gross return (₹ 95.58 × 10
3), net return (₹ 75.41 × 10
3), return per ₹ invested (4.74), B:C ratio (3.74) and system profitability (₹ 261.86 ha
-1 day
-1). This was in conformity with
Seran and Brintha (2010),
Segun-Olasanmi and Bamire (2010), they reported that the intercropping system gave higher cash return to smallholder farmers than growing as mono crops.
Energy budget
The energy budget for different maize based cropping system were also evaluated (Table 4) and the result revealed that among the sole cropping the lowest energy input was with the sole cropping of cowpea (7.75 × 10
3 MJ ha
-1). However, the highest output energy, net energy, energy efficiency and energy productivity was found with the cultivation of maize as 103.44 × 10
3 MJ ha
-1, 94.22 × 10
3 MJ ha
-1, 11.22 and 769.83 g MJ
-1 respectively. The result revealed that among the intercropping system (additive series) maize + cowpea (1:1) recorded the lowest energy input (9.52 × 10
3 MJ ha
-1) and maize + groundnut (1:1) recorded the highest output energy, net energy, energy efficiency and energy productivity 148.61 × 10
3 MJ ha
-1, 137.93 × 10
3 MJ ha
-1, 13.91 and 955.01 g MJ
-1 respectively. On the other hand, among the strip cropping system, maize + cowpea (4:4) recorded the lowest energy input (8.49 × 103 MJ ha
-1), highest energy efficiency (12.53) and productivity (955.01 g MJ
-1).