Precipitation and temperature regimes in upland Balochistan: Their influence on rain-fed crop production

Abstract

Rainfall and temperature regimes for three contrasting locations in the 200–250 mm annual precipitation zone of upland Balochistan are described, and their implications for crop production discussed. Rainfall dependability throughout upland Balochistan is generally low. Forty percent of median rainfall occurs during July and August at eastern and southern locations, permitting autumn sowing of winter cereals in six (Loralai) or seven (Khuzdar) years in ten; in contrast to western and northern areas (e.g. Quetta), where less than 10% of median rainfall occurs in summer, and autumn sowing can be expected in only two or three years in ten. Cumulative probabilities of sufficient rainfall for spring sowing are 93% for Quetta, but less than 60% for Loralai and Khuzdar. Mean maximum and minimum temperatures vary with elevation and location, ranging between 38 and −3°C, with up to 99 days below 0°C. The periods within which at least one frost may occur at 50% exceedence probability vary with location from 87 to 161 days. At the higher elevation location, Quetta, low temperatures delay spring planting, in contrast to the other locations where there is no serious temperature restriction for sowing. Upland Balochistan has one of the more severe climates for temperate crop production in West Asia, with low and undependable rainfall (partially relieved by water harvesting practices) and considerable cold stress at elevations above 1500 m. Cold-resistant, drought-tolerant winter crops are required for eastern and southern areas, and drought-resistant, short-season crops for more western and northern areas.