Vol. 6, Issue 5 (2018)
Molecular turnover time of soil organic matter in particle size fractions and soil organic matter alteration velocity of an arable soil through conservation agriculture: A review
Author(s): RK Naresh, RK Gupta, SS Dhaliwal, Vivek, Mukesh Kumar, Yogesh Kumar, DK Sachan, Sandeep Chaudhary, Saurabh Tyagi, KS Krishna Prasad and Lali Jat
Abstract: While soil organic carbon (SOC) accumulation and stabilization has been increasingly the focus of ecosystem properties, how it could be linked to soil biological activity enhancement has been poorly assessed. This paper reviewed the soil properties determined and to investigate niche specialization of different soil particle fractions in response to SOM alteration velocity. Conservation Agriculture (CA) can supply SOM, little is known about the temporal resolution of this change. Conventional tillage practices triggered SOM molecular size increases in both aggregates and the fine fraction, whereas switching to CA restored the molecular SOM size of the fine fraction only. Therefore, this fraction can be changed, even in short periods. Soil aggregates were fractioned into different sizes of coarse sand (200-2000 µm), fine sand (20-200 µm), silt (2-20 µm) and clay (< 2 µm), using separation with a low-energy dispersion protocol. Conservation Agriculture (CA) paradigm that is able to regenerate degraded land, minimize soil erosion, and harness the flow of ecosystem services.
The contribution of each aggregate class to soil C and N stocks changed with depth. Aggregates > 250 µm accounted for a similar percentage of C and N stocks in each layer: 64%, 59% and 50% in the 0-60, 60-200, and 200-400 kg soil m-2, respectively. Mid-size aggregates and small aggregates contributed increasingly to C and N stocks with increasing depth, accounting for 29%, 32% and 40% of the C and N stocks as mid-size aggregates and 7%, 9% and 10% as small size aggregates in the 0-60, 60-200, and 200-400 kg soil m-2 layers, respectively. The DOC concentration is considerably lower than those of other labile C fractions, generally not more than 200 mg kg±1, but it is the most mobile fraction of SOC. It controls the turnover of nutrient and organic matter by affecting the development of microbial populations. A positive relationship was observed between the 13C concentration in aggregates and the aggregate turnover rate.
The mass proportion both of coarse-sand (2000-200 µm) and clay (< 2 µm) fractions increased with prolonged cereal based cultivation, but the aggregate size fractions were dominated by fine-sand (200-20 µm) and silt (20-2 µm) fractions across the chronosequence. SOC was highly enriched in coarse-sand fractions (40-60 g kg−1) and moderately in clay fractions (20-25 g kg−1), but was depleted in silt fractions (∼ 10 g kg−1). The recalcitrant carbon pool was higher (33-40% of SOC) in both coarse-sand and clay fractions than in fine-sand and silt fractions (20-29% of SOC). However, the ratio of labile organic carbon (LOC) to SOC showed a weakly decreasing trend with decreasing size of aggregate fractions. Only in the coarse-sand fraction was both microbial gene abundance and enzyme activity well correlated to SOC and LOC content, although the chemical stability and respiratory of SOC were similar between coarse-sand and clay fractions. The finding here provides a mechanistic understanding of soil organic carbon turnover and microbial community succession and soil organic matter alteration at fine scale of soil aggregates that have evolved along with anthropogenic activity of cereal based cultivation in the field.
Pages: 1248-1264 | 376 Views 53 Downloads
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How to cite this article:
RK Naresh, RK Gupta, SS Dhaliwal, Vivek, Mukesh Kumar, Yogesh Kumar, DK Sachan, Sandeep Chaudhary, Saurabh Tyagi, KS Krishna Prasad, Lali Jat. Molecular turnover time of soil organic matter in particle size fractions and soil organic matter alteration velocity of an arable soil through conservation agriculture: A review. Int J Chem Stud 2018;6(5):1248-1264.
