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ARS Home » Midwest Area » Ames, Iowa » National Laboratory for Agriculture and The Environment » Soil, Water & Air Resources Research » Research » Publications at this Location » Publication #346604

Research Project: Managing Carbon and Nutrients in Midwestern U.S. Agroecosystems for Enhanced Soil Health and Environmental Quality

Location: Soil, Water & Air Resources Research

Title: Contributions of residue-C and -N to plant growth and soil organic matter pools under planted and unplanted conditions

item LI, ZENGQIANG - Chinese Academy Of Sciences
item ZHAO, BINGZI - Chinese Academy Of Sciences
item Olk, Daniel - Dan
item JIA, ZHONGJUN - Chinese Academy Of Sciences
item MAO, JINGDONG - Old Dominion University
item CAI, YUANFENG - Chinese Academy Of Sciences
item ZHANG, JIABAO - Chinese Academy Of Sciences

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2018
Publication Date: 5/1/2018
Citation: Li, Z., Zhao, B., Olk, D.C., Jia, Z., Mao, J., Cai, Y., Zhang, J. 2018. Contributions of residue-C and -N to plant growth and soil organic matter pools under planted and unplanted conditions. Soil Biology and Biochemistry. 120:91-104.

Interpretive Summary: Large amounts of nutrients enter a soil as the crop parts that remain in the field after harvesting. It is not fully clear to what extent these nutrients become part of the soil microorganisms, are taken up by the next crop, or remain in the soil. Little information is available on which soil microorganisms affect the distribution of the nutrients. We investigated these issues by using specially prepared plant materials. The results showed that the presence of a growing plant and the soil content of water affected nutrient movement in the soil and that a wide variety of microorganisms contributed to the nutrient movement. The results help better understand the complex interactions between plants, nutrients, and microorganisms in soil and will help guide improved management of crop nutrients. They are useful to soil scientists who study nutrients or soil microorganisms and to field managers of nutrients.

Technical Abstract: Soil microorganisms are considered the most effective decomposers of applied crop residues, but it is poorly understood which communities are primarily responsible for decomposition under different conditions. A pot experiment was conducted in a greenhouse to follow the cycling of C and N derived from maize (Zea mays L.) residues labeled with both 13C and 15N to a subsequent winter wheat (Triticum aestivum L.) crop and to soil pools. Soil microbes involved in residue decomposition were investigated by 13C phospholipid fatty acid (13C-PLFA) analysis technique. Treatments included planting with winter wheat (+P) or an unplanted control (-P), both in soil maintained at either less than 40% (W1) or at 80% (W2) of field moisture capacity. Residue N was recovered in either wheat plants or soil total N (TN), and residue C in soil organic carbon (SOC). At wheat maturity, greater percentages of residue N and C were recovered from the +P than the -P treatment (68% vs. 50% for residue N; and 33% vs 27% for residue C, respectively. The planted soil increased microbial biomass carbon and microbial biomass nitrogen by 35-48% and 38-75%, respectively, compared to the unplanted soil control and raised the total PLFA-C content by 6.7-14%. The PLFAs 16:0, 16:1w7c and 18:1w7c showed high relative abundances and altogether accounted for more than 44% of the total residue-derived PLFA-C in the planted soils. Either 16:0 and 18:1w7c or 16:0 and 16:1w7c showed high relative abundances in the unplanted soils, depending on water regimes. Only 16:1w7c and 18:17c had larger relative abundances in the planted than unplanted soil, suggesting that they were mainly stimulated by the presence of wheat and that they may be the most important fatty acids to define the different recoveries of residual N and C between the planted and unplanted conditions. More residue-C was recovered as SOC in oils at W2 than at W1 (35% vs. 24%), and total PLFA-C was also found to significantly increase with soil water contents. Only PLFAs 16:1w7c and 18:2w6,9c showed greater relative abundances at W2 than at W1, suggesting that they may be among the most important fatty acids to define the greater residual C recovery in the W2 conditions. Our results demonstrate the influence of plant growth on recovery of residue N and C by altering the activities of specific microorganisms.