Intensification and diversification of crop rotation in no-tillage agriculture rapidly differentially modified soil structure and soil biology.

GABBARINI L; DOMINGUEZ A; COVELLI J; FERRARI A; ROBLEDO B; FRENE JP; REYNA D; ORTIZ C; RODRIGUEZ P; FIGUEROLA ELM; ERIJMAN L; AGOSTI B; BEDANO JC; WALL LG

Leipzig

Simposio; 17th International Symposium on Microbial Ecology; 2018

ISME

In Argentina more than 22 million Ha are no-till cultivated lands. We have previously shown that the typical 3-years crop rotation in Argentina (wheat/soybean-corn-soybean) was enough to sustain bacterial diversity at the regional level, while mono-cropping reduced it. A group of no-till farmers gathered in AAPRESID goes further with this model and are studying the effects of intensifying and diversifying crop rotation on soil productivity and soil health. Starting with a single plot with a common no-till agriculture history, 5 different treatments with different intensification indexes of crop rotation (IIR) -calculated as: days of the year with plants / 365 -, ranging from 0,55 for typical crop rotation to 1 in the case of pasture, were assayed. Treatments were replicated at 3 locations. 5 soil subsamples were taken for each treatment in autumn and spring along two years. Enzymatic profiles, whole soil lipids fatty acid profiles, 16s DNA sequencing, meso- and macro-fauna abundance of different taxonomic groups, and proportion of soil micro-aggregates were analysed. After three years of treatments all biological and biochemical data were able to discriminate between soil treatments. Most biological activities, at different level of complexity, show good correlation with IIR. This correlation was improved when the C3/C4 nature of crops and the use of cover crop were taken into account in the IIR calculation. With all this data we are aiming to model soil structure and function in terms of crop rotation and to define new soil health indexes useful for farmers.