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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #181393
Title: SOIL CARBON DIOXIDE EFFLUX IN A CLAYPAN SOIL AFFECTED BY SURFACE COMPACTION AND APPLICATIONS OF POULTRY MANURE

Author
item PENGTHAMKEERATI, PATTHRA - UNIVERSITY OF MISSOURI
item MOTAVALLI, PETER - UNIVERSITY OF MISSOURI
item Kremer, Robert
item ANDERSON, STEPHEN - UNIVERSITY OF MISSOURI

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2005
Publication Date: 7/10/2005
Citation: Pengthamkeerati, P., Motavalli, P.P., Kremer, R.J., Anderson, S.H. 2005. Soil carbon dioxide efflux in a claypan soil affected by surface compaction and applications of poultry manure. Agricultural Ecosystems and Environment. 109(1-2):75-86.

Interpretive Summary: Soil structure is an important characteristic because it reflects the physical condition related to cultivation (“tilth”) and the manner in which soil particles are arranged (aggregated) that define soil porosity, which is the ability to hold and conduct water and air necessary for microbiological processes and plant growth. Because timely planting and harvesting of crops are affected by prevailing weather conditions, moist or wet soils are often subjected to the weight of farm machinery traveling over the soil surface and may become compacted, which weakens soil structure leading to reduced water infiltration and aeration, reduced microbial activity involved in nutrient cycling, and a poor seedbed for crop root penetration. We investigated the effects of soil compaction on microbial activity by measuring soil respiration as CO2 release (“efflux”) from a soil under corn production in North Central Missouri and the impact of an organic amendment (poultry manure) on modifying the effects of compaction on soil biological and physical properties. In a laboratory study, field-collected soils were either amended with poultry manure (28 g per kg of soil) or non-amended, artificially compacted by increasing the bulk density (dry soil mass per unit volume) using a hydraulic press, moistened, and incubated at ambient temperature. Periodic sampling showed that soil respiration decreased as bulk density (compaction) increased and as soil porosity (pore or air spaces) decreased. Addition of poultry manure, however, increased soil respiration in both compacted and non-compacted soils, especially early during incubation, suggesting that readily decomposable nutrients in the manure were rapidly metabolized by soil microorganisms before the effects of soil compaction limited availability of more complex nutrients. A subsequent field study in which soil was either amended with poultry manure (about 8.4 tons per acre) or with no manure, and where soil in half the field was compacted using a tractor-pulled water wagon containing about 500 gallons of water, also showed that soil respiration decreased as compaction increased. However, decreased respiration due to soil compaction was greatest during the second year of the study, which received more rainfall than the previous year. Poultry manure increased soil respiration with or without compaction in both years. The results suggest that incorporation of poultry manure may alleviate adverse effects of soil compaction by supplementing available nutrients for microbial activity. This information is important for scientists, extension personnel, and farmers because it will be useful in management of soil compaction effects on crop productivity, which could involve the use of an abundant resource, poultry manure, as an effective soil amendment.

Technical Abstract: The effects of soil compaction on soil physical properties may alter soil microbial activities and processes, including carbon (C) cycling, and possibly affect agricultural production and environmental degradation. The objective of this study was to investigate the effects of surface soil compaction on soil C mineralization in a claypan soil amended with poultry manure. In a laboratory study, a Mexico silt loam soil was compacted to four bulk densities (1.2, 1.4, 1.6 and 1.8 Mg m-3), with and without poultry manure treatments (0 and 28.3 g kg-1), and incubated at 25°C for 42 days. A field experiment was also conducted in 2001 and 2002 on the same claypan soil in North Central Missouri. Soil was amended with manure (0 and 19 Mg ha-1) by incorporation to a 15-cm depth and left uncompacted or uniformly compacted to approximate a bulk density of 1.4 Mg m-3. Compaction decreased soil CO2 efflux up to 72% in the laboratory study and 46% in the 2002 field study (P < 0.05). Compaction did not influence CO2 efflux in the 2001 field study. Manure application enhanced soil CO2 efflux (P < 0.05) due to the addition of readily available C from manure. In the laboratory study, soil CO2 efflux was negatively correlated with soil bulk density and the proportion of micropores (<5 'm radius; P < 0.05). Conversely, soil CO2 efflux was positively related with total porosity and the proportion of macropores (>500 'm radius; P < 0.05). In the field, surface soil compaction caused changes in soil water content and soil aeration, which may have had the greatest effect on variation in soil CO2 efflux. These results indicate that both soil compaction and manure application change soil C mineralization, and the magnitude of those changes is modified by climatic variation.