当前世界环境

Leh district is situated between 32-36° N latitude and 75-80° E longitude with an altitude ranging from 2500 to 6000 m above mean sea level. Leh is the largest district in the country with an area of 45,100 Km². Agriculture is the main occupation of the rural people of the district. Initial analysis of the data revealed that the acreage of wheat crop increased from 2003 onward. Notably, a simultaneous decrease in acreage of barley crop was observed. It is noticeable that wheat crop replaced the barley crop from 2003 onwards. Such change in cropping pattern was found related with change in weather condition. It was observed that from 2003 onward monthly mean of daily minimum temperature during May increased from 4 °C to 8 °C up to 2007. Similarly, monthly mean of daily maximum temperature was observed higher (>20 °C) before 2003 but decreased during 2003 to 2009 (range 15 to 20 °C). Snowfall was a common phenomenon during month of May before 2003, but was not observed during 2003 to 2009. Therefore, it is hypothesized that increase in both minimum and maximum temperature during May had enabled the farmers to grow wheat in place of barley. Moreover, during the month of April, snowfall events were significantly reduced in 2003-2009 and in month of May snowfall events was not recorded at all. This may perhaps another reason which enabled farmers to sow the wheat crop during last week of April to mid of May. Interestingly during last two years, the cropping pattern is again reversed. The acreage under wheat crop was decreased and the acreage under barley increased. Such reversal may be due to re-occurrence of snowfall events during first two weeks of May, which was absent during 2003-2009. Therefore, it is quite apparent that weather condition influenced the cropping pattern and crop acreage. However, many other factors like timely availability of seed, quality of seeds as per need of local farmers as they prefer some straw producing varieties, crop rotation pattern, etc., also plays some role in shifting of cropping pattern. Long term data base on crop-weather relationship among with the other factors may help in developing crop weather modeling.