effect of varying water regimes on zn and n dynamics and rice productivity in saline vertisols

Abstract

t is well established that zinc deficiency adversely affects on paddy yield. High newlinesalts and continuous submergence are two of the leading factors causing Zn deficiency in newlinesoils where paddy is cultivated. Continuous submergence of rice puts tremendous stress newlineon the already dwindling water resources. Paddy is cultivated in the zinc deficient black newlinesoils of Ballari district, Karnataka by submerging the fields through canal irrigation newline(Tungabhadra Project. These soils are increasingly becoming saline due to seepage, poor newlinesoil-water transmission characteristics and presence of sub-surface salinity and saline newlinegroundwater aquifers. These problems had affected significant chunk of fertile tracts and newlinecaused significant loss to paddy productivity. Thus there is a need to prepare adequate newlinecontingency plans to improve the productivity of such soils and to do with technology, newlinewhich is resource efficient, economically viable and environmentally safe. The present newlinestudy was devised with a view to find out effective solutions to the multipronged issues newlineof paddy cultivation in saline black soils of the district. The approaches followed were: newline(a) screening the most suitable salt-tolerant variety for paddy-growing black soils, newline(b) identifying appropriate water management strategy (WMS) to save water and improve newlinewater productivity without compromising on paddy yield, and (c) identifying the newlineoptimum zinc and nitrogen (N) fertilizer combination, overlaid on the best WMS to newlinealleviate Zn deficiency, improve Zn release and sustain high rice yield. newlineTo fulfil the above, laboratory, pot culture, rhizobag and field experiments were newlinecarried out at the ICAR- Indian Institute of Soil and Water Conservation, Research newlineCentre, Ballari, Karnataka during 2016-18. The pot culture experiment was conducted on newlinesaline black soils with seven salt tolerant paddy varieties (CSR 22, GGV 0501, NLR newline34449, MTU 1010, CO 43, TRY- 1 and TRY- 3) and three zinc levels (0, 37.5 and 50 kg ha-1) newlineunder controlled conditions on a completely randomized block design (CRBD)