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Post 30-years effects of conversion of sand dunes to rice ecosystem on soil organic matter, biological indices and micronutrient fractions in south-western Punjab, India
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  • Harinder Singh,
  • Pritpal Singh,
  • Sandeep Sharma,
  • Gobinder Singh
Harinder Singh
Punjab Agricultural University

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Pritpal Singh
Punjab Agricultural University
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Sandeep Sharma
Punjab Agricultural University
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Gobinder Singh
Punjab Agricultural University
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Abstract

In south-western Punjab, we investigated how the soil organic C (TOC) pool changed over time in undisturbed sand dunes and adjacent field, along with its labile and non-labile fractions, their relationships to micronutrient fractions, and the biological characteristics of the soil (India). To explore the effects of land use changed from sand dunes to intensive rice-wheat cropping system (RCWS) the soil samples were collected from both the undisturbed sand dunes and the adjacent fields converted to farmland about 30 years ago. The results showed that in comparison to RCWS soils, the TOC pools under sand dunes remained lower by ~2.5 g C kg -1 (about 86.2%) but, their active C pools (Fract. 1 + Fract. 2) were significantly better (by about 0.67 g kg -1; 40.4%). Similarly, the passive C pool (Fract. 3 + Fract. 4) was significantly higher in RCWS soils by ~3.1 g kg -1 (about 239%), compared with the sand dunes. The passive C comprised ~81.7% of TOC pool in RWCS soils that was only ~44.0% in sand dunes. Following land-use change, the RWCS fields gradually increased the TOC stocks by ~75% as compared to sand dunes. In RWCS, the soil alkaline-phosphatase (Alk-P) and dehydrogenase (DHA) activities was significantly higher by 4.6 to 6.7 times than the sand dunes. Besides, Micro-nutrients cations (e.g. Zn, Cu, Fe and Mn) and their transformations were also higher by ~1.7, 1.8, 2.9 and 5.2-times, respectively in RWCS than sand dunes. Likewise, total-Zn, total-Fe and total-Mn fraction in RWCS soils was ~77.3%, ~90.4% and ~64.4% higher than their respective contents in sand dunes. After 30 years of continuous RWCS system, the soil quality index increased from 0.23 to 0.97.These results clearly showed that due to increased soil microbial activities, the RWCS have significant potential to sustain C and build-up of micro-nutrients cations hence, underpins the clear signs of soil sustainability in south-western region of the Indian Punjab.