Impact of soil moisture depletions, planting geometry and soil texture on bio economic efficiency of autumn sugarcane under arid conditions

In arid areas of central Pakistan application of 2800 and 2200mm irrigation water in 28 and 22 irrigations on sandy loam and silty soils, respectively to autumn sugarcane through flooding is a common practice. Whether this irrigation depth and frequency is sufficient to fulfill the requirements of autumn sugarcane is not established. This study was conducted to evaluate the optimum water requirements by applying direct method of soil water measurement through gravimetric procedure. A three years field study was conducted on autumn sugarcane cv. HSF 240 at research area of MLL (Main Line Lower) Land Reclamation Research Station Chak No. 37 TDA (Thal Development Authority) Bhakkar, Pakistan on sandy loam and Gomal University Dera Ismail Khan Pakistan on silty clay soil from 2003–04 to 2005–06. The experiment was laid out in randomized complete block design with factorial arrangement in four replications and net plot size was 24m2. The four available soil moisture depletion levels under study were ASMDL1 (20%), ASMDL2 (40%), ASMDL3 (60%) and ASMDL4 (80%) and four planting patterns G1 (60cm), G2 (75cm) spaced single row planting patterns, G3 (30/90cm) and G4 (30/120cm) spaced paired row strip planting patterns were tested. The analysis of three years pooled data showed that maximum shoot dry weight, sugar yield, water use efficiency and benefit cost ratio were recorded in the treatment interaction of ASMDL2 (40%)×G3 (30/90cm) followed by ASMDL2 (40%)×G2 (75cm), ASMDL2 (40%)×G1 (60cm), respectively, whereas minimum in the interaction of ASMDL4 (80%)×G4 (30/120cm) at both soils. Maximum sugar recovery percentage (10.87 and 10.78%) was recorded in ASMDL4 (80%)×G4 (30/120cm) planting pattern and minimum values of 8.44 and 7.28% on sandy loam and silty clay soils, respectively was recorded in ASMDL1 (20%)×G1 (60cm) planting pattern. It was concluded that irrigation application on the basis of direct method of soil water measurement through gravimetric procedure saved 15.56 and 10.29% irrigation water by applying 38 and 23 irrigations keeping the depth of each irrigation 54 and 74mm on sandy loam and silty clay soils, respectively as compared with traditional method of irrigating autumn sugar cane crop through flooding under arid conditions. Therefore maximum bio economic benefits could be obtained from autumn sugarcane crop by irrigating it at 40% ASMDL and sowing in 30/90cm spaced paired row strips in arid conditions on sandy loam and silty clay soils.