Land and water productivity of wheat in the Western Indo-Gangetic plains of India and Pakistan: a comparative analysis.

Abstract

AbstractThis study was conducted to analyse variations in wheat yields and to assess the range of factors affecting wheat yields and the profitability of wheat production in selected irrigation systems in India and Pakistan. The constraints and opportunities for closing the existing yield gap were identified. It is hypothesized that substantial gains in aggregate yields can be obtained by improved water-management practices at the farm and irrigation-system levels. The study was conducted in the Bhakra canal system (BCS) in the Kaithal irrigation circle in India and the Lower Jehlum canal system (LJCS) in the Chaj sub-basin in Pakistan. Six watercourses, one each on the head, middle and tail reaches of one distributary in each country, were selected for detailed field-level data collection. Results showed that the average wheat yield in the selected irrigation system in India was higher (4.48 t ha-1) than that in the selected system in Pakistan (4.11 t ha-1), but not by as much as is generally perceived. However, the overall yield gap across farms was much wider in the study area in LJCS-Pakistan than that in BCS-India. Wheat-yield differences were much higher across watercourses (i.e. at the distributary level) than across distributaries. There was a significant inequity in distribution of canal water in the study areas in both BCS-India and LJCS-Pakistan, with tail reaches receiving less canal water than head and middle reaches. Groundwater use, as expected, was higher in reaches receiving less canal water and vice versa. The average productivity of consumed water was similar for the selected systems in both countries, i.e. 1.36 kg m-3 in India and 1.37 kg m-3 in Pakistan. However, average productivity of diverted water was higher for BCS-India (1.47 kg m-3) than for LJCS-Pakistan (1.11 kg m-3). In the study areas of both countries, average land productivity was lower in locations where groundwater was of relatively poorer quality. The groundwater quality within a distributary deteriorates towards the middle and tail reaches (except for Khadir in LJCS-Pakistan, where groundwater was less saline in the tail ends), and these reaches currently receive less canal water. Thus, intradistributary canal-water allocation is an important issue in reducing the yield gap. Using farm-level data, yield functions were estimated to analyse the effects of a range of production factors. Results showed that, in addition to improved farm-management practices, such as adopting new varieties, avoiding sowing delays and improved input applications, the improvements in water-management practices at the system level will also contribute to increased wheat yields and overall profitability. Improving timings of canal-water deliveries and adopting an effective canal-water reallocating strategy will result in overall socio-economic gains. In both BCS-India and LJCS-Pakistan, the profitability of wheat production decreases with the overall quality of the water used. The study presented alternative scenarios for the impacts of changes in the allocation of canal and groundwater on the socio-economics of wheat production. It is concluded that overall gains from wheat production can be increased by adopting effective reallocation of canal water at the distributary level. Many of the gains under the scenario will be in locations where groundwater is of poorer quality. The policy implication of this is that, under conditions of canal-water scarcity and variations in the quality of groundwater, joint management of canal water and groundwater is essential to increase overall gains from crop production. The study presented an example of 'institutional water scarcity' that could be addressed through effective institutions, leading to improved management of available surface-water and groundwater resources.