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Different types of agricultural cropping systems involving wheat coupled with rice, maize and cotton are adapted by most of the farmers around the world. In order to increase the production of food grains with the adaptation of these cropping systems, intensive cultivation is required which eventually needs more quantity of macro as well as micronutrients. The availability of micronutrients to plants is majorly affected by cropping patterns and their profile distribution and the chemical pools. For instance, rice–wheat (R-W) cropping system depletes the available micronutrients status in soil. Many crops have a deep root system that allows them to fulfill their micronutrients requirement from deeper soil layers. In pedon, the surface layer of soil is richer in micronutrients than sub-surface soils. Thus, the knowledge of all the forms or fractions of micronutrient in soil and conditions that help in converting them to their available forms is essential. Excessive use of macronutrient fertilizers in soil with alkaline pH, results in an upsurge accumulation of micronutrients under R-W system. Consequently, it is essential to understand the relationship between accumulation of micronutrients by plants and different chemical pools of micronutrients and their distribution in the pedon. Also, the incorporation of different crops in various cropping systems has a marked influence on microbial communities in soil which play a crucial role in nutrient cycling, gaseous exchanges, aggregation and soil biochemical processes that ultimately influences crop productivity and soil health. Thus, imaging the extent of micronutrient availability to plants, various fractions of micronutrients and microbial community in soil under different cropping systems is necessary.

Field experiments were conducted for two years on a sandy loam soil to evaluate various cyclic and mixing modes of irrigation with canal (0.6 dS m-1) and saline (12 dS m-1) waters on salinity buildup, water use, and yields of Indian mustard (Brassica juncea L.) and pearl millet (Pennisetum typhoides L.). Normalized to the treatment receiving canal water (100%), relative yield (RY) obtained with only saline irrigation averaged 56% in mustard. Application of canal water for presowing/first post-sowing irrigation (rossette stage) improved yields by 35 and 25%, whereas its application at later stages (siliquae formation) resulted in lesser compensation (13%). Alternating irrigations with canal and saline water were superior (95% relative yields) compared to mixing the two supplies in equal proportions and then irrigating (87%). Salinity-induced reduction in growth led to decreased branching and bearing capacity (siliquae per plant), whereas effects on seed test weight and seeds per siliqua remained statistically nonsignificant. Stepwise linear response function with time-averaged salinity (ECe, dS m-1, 0-0.3 m soil depth) could be described as RY = 100 - 8.5 (ECe- 3.8). Results also suggest increased salinity tolerance of mustard with aging. Salts accumulated during irrigations to Indian mustard did not affect the yields of the following pearl millet crop.