Carbon and Nitrogen Content of Soil Organic Matter and Microbial Biomass under Long-Term Crop Rotation and Tillage in Illinois, USA

Stacy Zuber,Emerson Nafziger,Maria Villamil,Gevan Behnke

doi:10.3390/agriculture8030037

Stacy Zuber, Emerson Nafziger + Show 2 more

Open Access

https://doi.org/10.3390/agriculture8030037

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Abstract

Crop rotation and tillage alter soil organic matter (SOM) dynamics by influencing the soil environment and microbes carrying out C and N cycling. Our goal was to evaluate the effect of long-term crop rotation and tillage on the quantity of C and N stored in SOM and microbial biomass. Two experimental sites were used to evaluate four rotations—continuous corn (Zea mays L.) (CCC), corn-soybean (Glycine max [L.] Merr.) (CS), corn-soybean-wheat (Triticum aestivum L.) (CSW), and continuous soybean (SSS), each split into chisel tillage (CT) and no-till (NT) subplots. The CSW rotation increased soil organic carbon (SOC) content compared to SSS; SSS also reduced total nitrogen (TN) compared to other rotations. Levels of SOC and TN were 7% and 9% greater under NT than CT, respectively. Rotation did not affect microbial biomass C and N (MBC, MBN) while tillage reduced only MBN at 10–20 cm compared to NT, likely related to dispersion of N fertilizers throughout the soil. Despite the apparent lack of sensitivity of microbial biomass, changes in SOC and TN illustrate the effects of rotation and tillage on SOM dynamics. The inclusion of crops with high C: N residues and no-till use both support higher C and N content in the top 20 cm of the soil.

Highlights

Crop rotation and tillage practices have a substantial influence on the soil as they alter the soil environment, influencing the habitat and energy source of the microbial community, the primary driver of soil organic matter (SOM) dynamics [1]
The impact of crop rotation on soil organic carbon (SOC) and total nitrogen (TN) in two Illinois soils was relatively minor, as differences in SOC were found only between CSW and SSS while SSS led to less TN compared to the corn-based rotations
The inclusion of high C: N ratio residues within a rotation help to maintain both C and N storage within SOM, but in comparison between different crop sequences, the frequency of these crops within the rotation only minimally affects the levels of SOC

Summary

Introduction

Crop rotation and tillage practices have a substantial influence on the soil as they alter the soil environment, influencing the habitat and energy source of the microbial community, the primary driver of SOM dynamics [1]. Microorganisms are responsible for the decomposition of organic matter inputs in the form of crop residues; as microbes break down residues, C becomes incorporated into microbial biomass, which becomes a key component of SOM [2]. Agronomic practices play a substantial role in influencing the cycling of C through the soil and microbial community, yet environmental factors inherent to the soil and location, such as initial SOM levels, soil texture, and climate, will affect the degree to which crop rotation and tillage influence SOM dynamics [5,6].

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