Soil Organic Carbon Fractions, Soil Microbial Biomass Carbon, and Enzyme Activities Impacted by Crop Rotational Diversity and Conservation Tillage in North West IGP: A Review

Abstract

Soil organic carbon (SOC) and its fractions (labile and non-labile) including particulate organic carbon (POC) and its components [coarse POC and fine POC], light fraction organic carbon (LFOC), readily oxidizable organic carbon, dissolved organic carbon (DOC) are important for sustainability of any agricultural production system as they govern most of the soil properties, and hence soil quality and health. Being a food source for soil microorganisms, they also affect microbial activity, diversity and enzymes activities. The content of OC within WSA followed the sequence: medium-aggregates (1.0-0.25 mm and 1.0-2.0 mm)> macroaggregates (4.76-2.0 mm)> micro-aggregates (0.25-0.053 mm) >large aggregates (4.76 mm) >silt+ clay fractions (<0.053 mm). The highest levels of MBC were associated with the 1.0-2.0 mm aggregate size class. The Cmic/Corg was greatest for the large macro-aggregates regardless of tillage regimes. The tillage treatments significantly influenced soil aggregate stability and OC distribution. Higher MWD and GMD were observed in plowing every 2 years (2TS), plowing every 4 years (4TS) and no plowing (NTS) as compared to plowing every year without residue (T). With increasing soil depth, the amount of macro-aggregates and MWD and GMD values were increased, while the proportions of micro-aggregates and the silt+ clay fraction were declined. The OC concentrations in different aggregate fractions at all soil depths followed the order of macro-aggregates>micro-aggregates>silt+ clay fraction. In the 0-5 cm soil layer, concentrations of macro-aggregate-associated OC in 2TS, 4TS and NTS were 14, 56 and 83% higher than for T, whereas T had the greatest concentration of OC associated with the silt+ clay fraction in the 10-20 cm layer. Tillage regimes that contribute to greater aggregation also improved soil microbial activity. Soil OC and MBC were at their highest levels for 1.0-2.0 mm aggregates, suggesting a higher biological activity at this aggregate size for the ecosystem. Compared with CT treatments, NT treatments increased MBC by11.2%, 11.5%, and 20%, and dissolved organic carbon (DOC) concentration by 15.5% 29.5%, and 14.1% of bulk soil, >0.25 mm aggregate, and <0.25 mm aggregate in the 0−5 cm soil layer, respectively. The portion of 0.25-2 mm aggregates, mean weight diameter (MWD) and geometric mean diameter (GMD) of aggregates from ST and NT treatments were larger than from CT at both 0-15-and 15-30-cm soil depths. Positive significant correlations were observed between SOC, labile organic C fractions, MWD, GMD, and macro-aggregate (0.25-2 mm) C within the upper 15 cm. The arylsulfatase, β-glucosaminidase and α-glucosidase activities showed a significant increase in the enzyme activities due to crop rotations in comparison to continuous mono-cropping. The activities of chitinase, leucine aminopeptidase and tyrosine aminopeptidase) in the topsoil layer were higher under conservation agriculture (CA).Moreover, compared with CT, the ZT and FIRB treatments significantly increased nitrifying [Gn] and denit...

Growth analysis and yield evaluation under tillage and weed management practices in maize-wheat cropping system

“…This might be due to the reason that conservation agriculture had improved soil properties, better crop establishment and minimum lodging. Similar results were reported by Jat et al (2017) and Chaudhary et al (2018). Although, harvest index was higher in ZT-ZTR in maize and CT-ZT in wheat crop.…”

“…Other major problems like imbalance use of pesticides, nutrients deficiencies or imbalances, high energy and labour requirement and weed shift cause threat to the sustainability of cereals based cropping system (Pathak et al, 2011;Ram et al, 2012). Many studies have shown that continuous no-tillage for long term increases soil organic matter (Bhattacharyya et al, 2009;, soil health, improve soil structure (Jat et al, 2018) and increases crop yield substantially than intensive tillage practices (Cannell and Hawes, 1994). Therefore, conservation strategies and modern farming techniques must be incorporated in the indigenous production systems for environmental protection, economic and social development and ecologically sustainability (Singh and Rao, 2002).Therefore, an experiment on maizewheat cropping sequence was conducted to study the effect of tillage in relation to weed management on crop DMA, growth indices and biological yield in the North-Western Himalayas.…”

Effects of Conservation Tillage and Weed Management On Soil Microbial Community and Enzymatic Activity

“…Liu et al (2016) revealed that MBC concentration was significantly higher under zero tillage treatments. Acid phosphatase activity was greater under zero tillage than under conventionally plowed plots with a disk harrow and disk plow (Chaudhary et al 2018). Results from the present study showed that on a short-term basis, soil microbial dynamics and activities are highly influenced by the method and degree of tillage practices along with either incorporation of residue is done or not and different tactics of weed management used in maize wheat cropping system.…”