Rice straw application with different water regimes stimulate enzymes activity and improve aggregates and their organic carbon contents in a paddy soil

Ibrahim Mohamed; Mohamed A Bassouny; Mohamed H H Abbas; Zhan Ming; Cao Cougui; Shah Fahad; Shah Saud; Jabar Zaman Khan Khattak; Shamsher Ali; Haythum M S Salem; Ahmed Azab; Maha Ali

doi:10.1016/j.chemosphere.2021.129971

Rice straw application with different water regimes stimulate enzymes activity and improve aggregates and their organic carbon contents in a paddy soil

Chemosphere. 2021 Jul:274:129971. doi: 10.1016/j.chemosphere.2021.129971. Epub 2021 Feb 15.

Authors

Affiliations

¹ Department of Soils and Water Science, Faculty of Agriculture, Benha University, Benha, Qalyubia, Egypt.
² College of Plant Science and Technology, Huzahong Agricultural University, Wuhan, Hubei, 430070, China.
³ College of Plant Science and Technology, Huzahong Agricultural University, Wuhan, Hubei, 430070, China. Electronic address: ccgui@mail.hzau.edu.cn.
⁴ Department of Agronomy, The University of Haripur, Haripur, 22620, Pakistan. Electronic address: shah_fahad80@yahoo.com.
⁵ Department of Horticulture, Northeast Agricultural University, Harbin, China.
⁶ Department of Biological Sciences, International Islamic University (IIU), Islamabad, Pakistan.
⁷ Department of Soil and Environmental Sciences, Amir Muhammad Khan Campus Mardan, The University of Agriculture, Peshawar, Khyber Pakhtunkhwa, Pakistan.
⁸ Agricultural Engineering Research Center Institute (AEnRI), A.R.C, Giza, Egypt.

PMID: 33979915
DOI: 10.1016/j.chemosphere.2021.129971

Abstract

Soil organic carbon plays considerable roles in binding soil particles together forming aggregates. Carbon (C) incorporated within these aggregates is thought to be microbially processed; thus, investigating changes in microbial activities i.e. dehydrogenase, urease, catalase and phosphatase enzymes may explain, to some extent, the dynamics and probably mechanisms responsible of formation of these aggregates. Since, soil water content (SWC) may take part in stimulating/lessening activities of organic matter decomposers; thus, this study aimed at investigating the effects of rice straw as a source of organic C in combination with variable SWC on bioaccumulation of C within different soil aggregate size fractions (2000-250, 250-53 and < 53 μm) and hence formation of these aggregates. To achieve these objectives, a pot experiment was conducted for 90 days, including five water levels i.e. maintaining a water head 1 cm above the soil surface (W1), 100% of the saturation percentage, SP (W2), 80% of SP (W3), 65% of SP (W4) and 50% of SP (W5), beside of two rates of applied rice straw i.e. 0 and 15 g kg^-1 (w/w). Results revealed that application of rice straw at a rate of 15 g kg^-1 increased the activities of dehydrogenase, urease, neutral phosphatase and catalase enzymes within the first 60 days after application; thereafter, activities of the first three enzymes decreased considerably. Likewise, formation of soil macro- (2000-250 μm) and micro-aggregates (250-53 μm) increased by the end of the experimental period. The highest concentrations of soil carbon were incorporated within soil macro-aggregate, whereas the least C content was found within the "silt + clay" fraction. Increasing SWC resulted in significant reductions in activities of the aforementioned enzymes and consequent reductions occurred in soil aggregation. Carbon content within aggregates sized <250 μm were significantly correlated with the percentage of these aggregates in soil. Thus, soil aggregation is thought to be the byproduct of an aerobic biosynthetic microbial process in which more stable hydrophobic organic C existed mainly in macropores. This process probably occurred within the first 60 days after RS application.

Keywords: Anthrosols; Enzymes activity; Organic carbon; Rice straw; Soil aggregates; Water regimes.

MeSH terms

Agriculture
Carbon
Oryza*
Soil*
Water

Substances

Soil
Water
Carbon