Managing soil salinity with permanent bed planting in irrigated production systems in Central Asia

Mina Devkota Wasti, Christopher Martius, Raj Gupta, K. P Devkota, Andrew McDonald, John Lamers. (1/4/2015). Managing soil salinity with permanent bed planting in irrigated production systems in Central Asia. Agriculture, Ecosystems and Environment, 202, pp. 90-97.

Abstract

Land degradation due to water logging and its inﬂuence on secondary soil salinization processes pose a majorthreattothesustainabilityofirrigatedagricultureinthesemi-aridproductionecologiesofCentral Asia.Inrainfedconditions,conservationagriculture(CA)practices,i.e.,reducedtillage,residueretention and crop rotation, have proven to have substantial scope for arresting or reversing soil degradation. Previous research ﬁndings suggest that CA can be beneﬁciallyapplied to irrigated croplands as well, but inﬂuences on salinization processes are insufﬁciently documented. This study investigates the effect of CApracticesonsoilsalinitydynamicsinirrigatedproductionsystemsintheKhorezmregion,Uzbekistan, Central Asia. The study was conducted under a cotton-wheat-maize rotation system, typical for the region, from 2007 to 2009 with two tillage methods (‘CA’–permanent raised beds (PB); conventional tillage(CT))combinedwithtworesiduelevels(residueharvested(RH);residueretained(RR)).Compared to pre-experiment levels, salinity in the top 30cm soil increased signiﬁcantly during cotton (May– October), while a negligible change occurred during wheat (October–June) and maize (July–September) season.Inabsenceofcropresidues,soilsalinityontopofthebedsincreasedcomparedtoCTwithoutcrop residueretention.Whenretainingcropresidues,thesoilsalinityunderPBwasreducedby32%inthetop 10cm and by 22% over the top 90cm soil proﬁle compared to CT without crop residue retention. Thus, PB+RR seemsapromisingoptiontoslowdownon-goingsoilsalinization insalt-affectedagro-ecologies such as those in the irrigated arid lands of Central Asia.