Agro-economic Advantages of Different Canola-based Intercropping Systems

Introduction

Intercropping not only enhances the farm productivity but also provides security against the potential risks of monoculture. It helps in providing the diversified needs of the small farmers (Faris et al., 1976) who, in general practice subsistence farming. Thus it is imperative to look for such intercropping systems which have the potential of raising minor crops successfully in association with other crops of Pakistan like canola. Intercropping in canola has been reported to increase bio-economic efficiency of a farm determined in terms of canola seed yield equivalent, land equivalent ratio (Khan et al., 1988), area-time equivalent ratio and net field benefits (Bajwa et al., 1992) substantially over the monocropping of canola. Thus keeping in view, the importance of intercropping in intensive agriculture of Pakistan, the present study was planned to assess the agro-economic advantages of some canola-based intercropping systems under agro-climatic conditions of Faisalabad.

Materials and Methods

The present study was conducted at the Agronomic Research Area, University of Agriculture, Faisalabad during winter season of 1999-2000 and repeated in the same season in 2000-2001. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Intercropping systems were: no intercropping (sole canola), canola+one row of wheat, canola+two rows of wheat, canola+one row of gram, canola+two rows of gram, canola+one row of lentil, canola+two rows of lentil, canola+one row of linseed and canola+two rows of linseed. Plot size was 2.4 x 5.1 m². For the monoculture of gram, lentil and linseed the net plot sizes were also 2.4 x 5.1 m² but for wheat, it was 2.5 x 5.1 m². Seed bed preparation was uniform for both sole cropping and intercropping. The same varieties of canola (Hyola-401), wheat (Inqlab-91), gram (Bittal-98), lentil (Masoor-93) and linseed (Chandni) were used during both the years. Canola was sown on 14th October with a single row hand drill in 60 cm spaced paired row strips (60/20 cm). Intercrops were sown on 23rd October along with monoculture of wheat, gram, lentil and linseed. All the crops except wheat thinned twice to maintain optimum plant population. A basal dose of 90 kg N and 60 kg P₂O₅ ha^-1 was applied in all the treatments. Three irrigations were applied at different growth stages of canola. All other agronomic practices were kept normal and uniform for all the treatments. Both sole and intercrops were harvested manually and tied into separate bundles. The sun dried crops were threshed manually. Canola seed yield equivalent was computed by converting the yields of intercrops into the seed yield of canola, based on the market price of each intercrop (Anjeneyulu et al., 1982). Land equivalent ratio (LER) and area-time equivalent ratio (ATER) were computed using the formulae described by Willey (1979) and Hiebsch (1980), respectively.

Results and Discussion

Canola seed yield equivalent (CSYE)
Canola seed yield equivalent is the seed yield of canola plus yield of an intercrop transformed into canola seed yield. CSYE of all intercropping systems was higher than seed yield of the monocropped canola, which indicates advantage of intercropping in canola over the sole canola. The maximum CSYE was obtained from canola+one row of wheat followed by canola+two rows of wheat, canola+one row of linseed, canola+one row of gram, canola+two rows of linseed, canola+one row of lentil, canola+two rows of gram and canola+two rows of lentil. Singh et al. (1992) and Khan and Saeed (1997) reported considerable increase in wheat grain yield equivalent (WGYE) due to intercropping. The difference among CSYE of different intercropping systems were attributed to the variable price and yield of the component crops (Table 1).

Land equivalent ratio
Land equivalent ratio (LER) is the relative area of sole crop required to produce the yield achieved in intercropping (Khan et al., 1988). It is usually stipulated that the level of management must be the same for intercropping as for sole cropping. LER values were greater than one in all the intercropping systems except canola+one row of gram and canola+two rows of gram, indicating the yield advantage of intercropping over sole cropping of canola. Based on two years average data, total LER ranged between 1.00-1.24 ha^-1 in different intercropping systems. It means that maximum agronomic advantage of intercropping over monocropping is 24% in these canola-based intercropping systems.

Table 1:	Canola seed yield equivalent, land equivalent ratio, area-time equivalent ratio and net income as affected by different canola-based intercropping systems

In other words, it is possible to harvest yield from one ha of intercropping equivalent to that from 1.00-1.24 ha of sole cropping of canola. Singh and Gupta (1994) and Patrick et al. (1995) also reported higher LER for intercropping than that for sole cropping.

Area-time equivalent ratio
Since LER does not take into account the time for which land is occupied by the component crops of an intercropping system, area-time equivalent ratio (ATER) was also determined. On the basis of two years average data, ATER values indicated an advantage of 16, 14, 6 and 3% in canola+one row of wheat, canola+two rows of wheat, canola+one row of linseed and canola+two rows of linseed, respectively. While, other four treatments showed disadvantages by 0.01-0.05%. Higher value of ATER in intercropping treatments compared with monoculture of canola might be attributed to efficient utilization of natural (land solar radiation) and added (fertilizer, water) resources. Higher ATERs have also been reported in corn+cowpea (Allen and Oburo, 1983), wheat+methra and wheat+linseed (Khan and Saeed, 1997), associations compared with monocultures of the component crops.

Net income
All the intercropping systems gave higher net income than monoculture of canola except canola+two rows of gram and canola+one row of lentil. Canola+one row of wheat gave the maximum net income followed by canola+two rows of wheat, canola+one row of linseed, canola+one row of gram, canola+two rows of linseed and canola+two rows of lentil, against the minimum in canola+two rows of gram.

It is evident from the above discussion that intercropping in canola can go a long way in enhancing the agro-economic advantages to farmer under Faisalabad conditions if the component crops (especially wheat) grown in independent strips and are properly managed.