Impact of long-term conservation agriculture practices on crop productivity and soil and environmental health

Abstract

Given the increasing scarcity of production resources such as water, energy and labour coupled with growing climatic risks, maize-based production systems could be potential alternatives to intensive rice-wheat (RW) cropping system of north western Indo-Gangetic Plains (IGP). Adoption of conservation agriculture (CA) in maize based systems is widely promoted for minimizing soil degradation and ensuring sustainability under changing climate. Alternative tillage management practices are important strategies for tackling the issues of soil health deterioration, lower profit margins particularly in cereal based intensive crop rotations. We hypothesized that improved agricultural practices suited to production systems and agro-ecologies, such as zero tillage (ZT) and permanent beds (PB) may result in improving crop productivity and positive changes in soil health indicators. Therefore, a longterm study was initiated to assess the effect of three tillage and crop establishment practices [zero tillage, ZT; permanent beds, PB; and conventional tillage, CT] on crop productivity, soil and environmental health under four diversified cropping systems i.e. maize-wheat-mungbean (MWMb), maizechickpea- sesbania (MCS), maize-mustard-mungbean (MMuMb) and maize-maize-sesbania (MMS) continuous maize (Zea mays L.)-wheat (Triticum aestivum L.)- mungbean (Vigna radiata L. Wilczek) in a sandy loam soil (Typic Haplustept) of north-western Indo- Gangetic plains of India. In long-term, across the soil depths, soil organic carbon (SOC) content, its pools and mineral-N fractions were significantly affected by different tillage & crop establishment methods and diversified maize based cropping systems. CA based ZT and PB practices significantly increased the SOC stock (0- 30 cm depth) as compared to initial status. Several researchers also reported that SOC and mineral-N fraction contents in the top 30 cm soil depth are correlated with N2O-N emission. In our study, global warming potential (GWP) under CT system was higher by compared to CA-based ZT and PB, respectively. This might be due to that the several soil and environmental factors influence soil N2O emission and are controlled by a variety of management practices such as type of fertilizers (Albanito et al., 2017), fertilizer application method and time (Tenuta et al., 2015), crop type (Albanito et al., 2017), and tillage practice (Parihar et al., 2018). In current study, the lower N2O emission in ZT and PB can be attributed to increased oxygen diffusion rate into the soil promoting aerobic condition thereby reducing denitrification-led N2O emission. The results of our study suggest that CA and diversified crop rotations should be promoted in north-western IGP and other similar agro-ecologies across the globe for improving crop productivity, soil health restoration and climate change mitigation.