Intercropping (growing two or more than two crops simultaneously on the same field) is one of the way ameliorating the productivity of land and other inputs (Andrew and Kassam, 1976). Intercropping can be used by small farmers primarily to increase the diversity of their products and the stability of their annual output through effective use of land and other resources (Faris et al., 1983). Enyi (1973) reported that small farmers in many countries are seriously constrained by low productivity and limited land resources. Therefore, preliminary research has shown that possible means of increasing the productivity through intercropping. Willey and Osiru (1972) recommended that intercropping of maize with legumes appears to be more profitable, when legumes are intercropped at proper stand.
Mixtures of cereals and legumes have shown higher yields as compared to their sole cultivation. Crookston and Hill (1979) reported that when corn and soybean were drilled in alternating rows and alternating pairs rows, land equivalent ratios (LER) of 1.3 were obtained for both the treatments. Thiyagarajan (1994) reported decrease in the 100 grains weight of soybean in intercrop with maize. Huges and Metcalfe (1972) reported reduction in grain yield of intercrop soybean as compared to monoculture. Odango et al. (1990) observed that Maize depressed the grain yield of intercrop soybean. Cunared (1976) obtained LER ranging from 1.2- 1.5 from growing corn and edible soybean togather. Khan et al. (1999) reported that net income of Rs. 22789 ha-1 was obtained from intercropping maize and soybean. Pardaker et al. (1993) who observed clear monetary advantage of maize and soybean intercropping over monoculture.
The shortage of edible oil is the burning problem of the country. Soybean is an oil seed crop and has the potential to overcome the shortage of oil. During 1998-99 maize was grown on 962.2 thousand hectares. (Anonymous, 1998-99). If this area is brought under the intercropping of soybean with maize, enormous increase in soybean production can be achieved. To obtain the maximum yield of the component crops in the intercropping system, optimum seed rate is very important. The objective of this study was to determine the production effectiveness of soybean intercropping with maize under various seed rates of soybean.
Materials and Methods
This intercropping experiment was carried out at the research fields of NWFP
Agricultural University, Peshawar, during kharif season, 2000. The experiment
was carried out in randomized complete block (RCB) design with a net plot size
of 5x4.5 m2. A basel dose of 60 kg nitrogen and 60 kg phosphorus
per hectare was applied at the time of sowing, while 60 kg nitrogen per ha was
applied only to the maize crop with first irrigation. Maize (Kisan) was sown
with row to row distance of 75 cm while two rows of soybean (wahab-93) were
intercropped among maize rows having a row to row distance of 30 cm with treatments
||Maize and soybean intercropping and monoculture treatments
under various seed rates of
|T1, T2, T3= Inter croping;
T4= Maize monoculture;
T5, T6, T7= Soybeen monoculture.
Data were recorded on thousand grains weight (g), grain yield (kg ha-1) and land equivalent ratios (LER) of both the crops. Economic analysis was also performed to judge the economic effectiveness of the treatments.
LER is the land required for sole crops to produce the yield achieved in intercropping mixture. This provides measure of efficiency of particular crop association relative the sole crop (Willey, 1979) and is the most important index of measuring biological advantage of intercropping as compared to corresponding mono cropping system. This parameter is derived by calculating the absolute yield of each inter planted species to its yield in monoculture i.e. its relative yield and then summing the relative yields of all inter planted species to get the land equivalent ratios. LER greater than one indicated a more efficient use of land by the intercrops and the larger this value, the greater the efficiency of land use. Economic analysis was calculated by using the market prices of the crops prevailed at the time of harvest. To perform the economic analysis, first of all adjusted yield was worked out as prescribed by CIMMYT (1988) with the help of following formula:
Adjusted yield = Actual yield x 0.9
Gross income was calculated by multiplying the adjusted yield of each treatment by the current per kg price of the crop which was Rs. 10 kg-1 for soybean and Rs. 7 kg-1 for maize. Net income was computed by subtracting the cultivation cost from gross income. Cultivation cost includes seed cost, fertilizer (urea, DAP cost) land preparation charges, pesticide charges, ploughing, planking, sowing cost, weeding (two times) irrigation, harvesting, threshing
and transportation charges. BCR values (return per rupee invested) were calculated as follows (Akhtar et al., 2000):
Results and Discussion
Thousand grains weight: Analysis of variance showed that there was non significant effect on thousand grain weight of maize when intercropped with soybean at any seed rate. Thousand grain weight of soybean was recorded significantly (P≤ 0.05) higher in sole plots as compared to intercrop. Thousand grain weight of soybean in mono culture was recorded from 109.66 to 114.66 g, while thousand grain weight of soybean was decreased from 103.33 to 101.33 g when intercropped with maize at various seed rates (Table 2). The possible reason could be that in intercrop soybean, competition among the plants of two species was intensified that affected the growth of soybean resulted in poorly filled grains. This finding is confirmed by Thiyagarajan (1994), who reported a significant decrease in 100 grains weight of intercrop soybean.
Grain yield (kg ha-1): Results indicated that there was a non-significant effect of intercropping on the yield of maize. Soybean yield was significantly (P ≤ 0.05) reduced in intercrop with maize as compared to monoculture at all seed rates of soybean. Highest grain yield of soybean of 4131.00 kg ha-1 was obtained in monoculture at seed rate of 80 kg ha-1 (Table 2). Minimum grain yield of soybean of 1092 kg ha-1 was recorded in intercrop soybean seeded at 40 kg ha-1. Among intercrop treatments, maximum grain yield of 2382 kg ha-1 of soybean was recorded at seed rate of 80 kg ha-1. Monoculture recorded higher grain yield as compared to intercrop at all seed rates of soybean. These findings are with close conformity with those reported by Huges and Metcaife (1979) and Odango et al. (1990), who stated that intercrop maize depressed the grain yield of soybean.
Land utilization efficiency: The land equivalent ratios (LER) of intercrops provides an accurate assessment of the competitive relationship between the component crops, the best usage of land as well as the over all productivity of the intercropping system.
It is evident from the data that maize-soybean interropping produced significantly greater LERs than monoculture. LERs in intercropping ranged from 1.39-1.52 by using different seed rates of soybean (Table 2). These results agree with those reported by Cunared (1976) and Crookston and Hill (1979).
Economic analysis: Agro-economic feasibility of intercropping system is ultimately determind by its monetary gain. No single index is capable of giving a good comparison of intercropping system and so a number of indices are used togather to assess the economic viability of the system. The agronomist decides on the biological efficient, while the economist decides on the economic worthiness of the system using one or more than one of the economic indices. In general, a biological efficient system is also economically effective but quite often it so happens that a biologically efficient system is not economically viable and can not be recommended for wide scale adoptation by farmers.
An estimate of the economic aspect of the present studies were computed and
the data regarding monetary gain along with all relevant calculations and interpretation
is presented in Table 3. It is evident from the data that
maximum gross income of (Rs. ha-1) 51236, net income of Rs. 29978
and return per rupee invested of Rs 2.41 was obtained in maize and soybean intercropping
sown at soybean seed rate of 80 kg ha-1.
|| Thousand grains weight, grains yield (kg ha-1)
and LER values of maize and soybean intercropping at various seed rates
|LER: Land equivalent ratio, NS: Non significant at 5% probability
level. Means followed by different letters are significantly different from
each other using 5% level of probability
|| Economic analysis of maize and soybean intercropping under
various seed rates of soybean
Next in order was also intercrop at soybean seed rate of 60 kg ha-1,
which gave gross income of Rs. 46440, net income of Rs. 25943 and return per
rupee invested of Rs. 2.26. Intercrop recorded higher economic return as compared
to monoculture at all seed rates of soybean. These findings are with close conformity
with those reported by Khan et al. (1999) and Pardaker et al.
(1993), who observed clear monetary advantage of intercropping over monoculture.
It is concluded from the present findings that intercropping resulted in greater
productivity per unit of land and greater economic return as compared to monoculture,
especially when raised at proper stand of companion crop. However, further research
is suggested to devise a viable intercropping system regarding planting geometry
of these crops.