Responses of Microbial Nutrient Acquisition to Depth of Tillage and Incorporation of Straw in a Chinese Mollisol

Abstract

Tillage and straw incorporation are important agricultural practices that can break the plow layer and improve Mollisol fertility. The effect of these practices on the limitation of resources for soil microorganisms, however, is unclear. We established a field experiment in 2018 and collection of soil samples in 2020 to study the acquisition of resources by microbes in a Mollisol region in northeastern China. Four treatments were studied: conventional tillage (CT), straw incorporation with conventional tillage (SCT), subsoil tillage (ST) and straw incorporation with subsoil tillage (SST). The limitation of resources for soil microorganisms was assessed using models of extracellular enzymatic stoichiometry. The soil microbes were generally colimited by C and P but not N. The degree of limitation, however, varied among the treatments. SCT and SST alleviated microbial P limitation in the 0–15 and 15–35 cm layers, respectively, but ST did not significantly affect P limitation relative to CT. Interestingly, N-resource contents were strongly correlated with indicators of C and P limitation. A random forest analysis found that the contents of available N and total dissolved N were the most important factors for microbial C and P limitation, respectively. Straw incorporation alleviated microbial P limitation but did not eliminate P limitation and deep tillage aggravate microbial C limitation. We suggest that N fertilization may be reduced due to the N-rich characteristics of the Mollisols in northeastern China.

Inversion Tillage Combined with Organic Fertilizer Application Increased Maize Yield via Improving Soil Pore Structure and Enzymatic Activity in Haplic Chernozem

“…The lack of a water-storing structure in the topsoil leads to insufficient soil moisture and less leaching of carbonates, which leads to a thick caliche that inhibits the growth of microorganisms and the accumulation of soil organic matter [24]. To prevent the degradation of Chernozems, appropriate soil management practices have been recommended, including the application of organic fertilizer and crop straw, as well as inversion tillage [15,25,26]. The conventional tillage method using a 20 cm rototiller blade results in a shallow cultivated horizon of approximately 15 cm.…”

Microbial enzymatic stoichiometry and the acquisition of C, N, and P in soils under different land-use types in Brazilian semiarid

“…One method to estimate the nutrient demands by microbes and C, N, and P availability in soils is the stoichiometry of C-, N-, and P-acquiring enzymes (Sinsabaugh et al, 2009) and it has been applied in several previous studies (Zhang et al, 2021;Araujo et al, 2022;Pereira et al, 2023). In addition, the enzymatic stoichiometry can indicate which conditions C, N, and P are limited to soil microorganisms.…”