THE world during the 21st century will be facing shrinkage of land resources, increasing small holdings, pressure of rising population and accumulation of the world resources with the developed nations and consequently more hungry faces in the poor developing nations. To overcome these constrains and challenges, there is a need to revolutionise the agricultural system and to make it economic-based to meet the increasing food demands.

The present system of sole cropping has failed to meet the diversified domestic needs of small farmers. There is a need to shift from mono-cropping to multiple cropping (intercropping) which is as an excellent strategy to intensify land use, absorb excess labour, and increase income and production per unit area and time. This system has been frequently used in tropical and developed nations, such as the U.S. and Canada.

Intercropping of cereals and legumes is important for the development of sustainable food production systems, particularly in cropping systems with limited external inputs. Legumes have long been recognised as important components of crop rotations and intercrops. The direct benefits of nitrogen fixation in root nodules of leguminous plants contribute to soil fertility which can be used by subsequent or companion crops.

In agricultural settings, about 80 per cent of this biologically fixed nitrogen comes from symbiosis involving leguminous plants and species of Rhizobium. Worldwide, legumes are grown on approximately 250 million hectares and they fix about 90 million tones of nitrogen per year. It has been found that gram and lentil can fix nitrogen up to 67-141 and 62-103 kg per hectare respectively. In the past mono-cropping of grain legumes (pulses) was a usual practice among growers but now-a-days the interest in growing food legumes in an intercropping system is increasing.

Barley (Hordeum vulgare) has the widest ecological range among cereals. It is comparatively more tolerant to salinity, alkalinity, frost and drought conditions than other Rabi season crops. Farmers of arid and semi-arid regions of the country prefer this crop, because it requires less water and does well even with saline water. It is the second most important winter cereal after wheat in Pakistan. It offers a great opportunity to bring this marginal area under cultivation, where other crops like wheat cannot be grown.

No doubt, Pakistan has made remarkable improvement in its agriculture sector, but it is facing a chronic shortage in edible oils and pulses. The situation is getting worse day by day with its alarmingly increasing rate of population growth. The area under Rabi pulses and oilseed crops is limited and cannot be increased due to competition with cereals. Therefore, the only option left is to grow legumes and oilseeds in association with Rabi cereals to increase production of these crops.

The present study, therefore, has been planned to explore the possibility of legumes and non-legumes intercropping in barley with the following objectives:

To explore feasibility, production potential, and economics of different barley-based intercropping systems; to determine the agro-physiological relationships of the component crops in different barley-based intercropping systems at different levels of fertility; to determine the impact of various intercropping systems on residual soil fertility.

All the associated cultures reduce the yield of barley to a significant level. However, the additional harvest obtained from the associated cultures compensated more than the losses in barley production. Sufficiently higher net field benefit was obtained from intercropping treatments than the sole cropping of barley. Highest net field benefits of Rs44,402 per hectare were recorded for barley + methra against the minimum of Rs31,747 ha-1 for barley + linseed.

In term of economics and yield advantages, all the barley-based intercropping systems gave higher LER (Land equivalent ratio) and net income ha-1 than mono-cropping of barley. Barley growth was more suppressed with canola companion crop due to its vigorous vegetative growth rate and shading effect. Soil nitrogen and organic matter was improved in all the legume-intercropping systems compared to the sole barley as well as non-legume intercropping systems, however, the maximum increase in soil nitrogen was recorded for barley + methra intercropping system.

Therefore, intercropping of barley with legumes and non-legumes is recommended as a potentially useful technology, especially for small and marginal farmers with plenty of family labour but limited land and economic resources. Under the present circumstances, farmers with small holdings and seriously constrained by low crop income due to very low yields and sometimes complete crop failure, can adopt the practice of intercropping of barley with different legumes and non-legumes crops to cover the risk of complete crop failure or very low crop income.

On the basis of economic analysis it is recommended that small farmers with limited resources may adopt barley + methra or barley + lentil intercropping systems. There is need for further improvement in barley-based intercropping technology considering intercrop duration, cultivation methods, type of intercrop and location should be focus.

There is also need to monitor the long-term residual effects of different barley-based intercropping systems on the productivity of the following crops, residual soil fertility and soil health to plan strategies leading to sustainable agricultural production in the country. There is also need to develop appropriate machinery/drill for strip planting to facilitate intercropping on a large scale in the country.