|THAPA, VESH - New Mexico State University|
|GHIMIRE, RAJAN - New Mexico State University|
|IDOWU, OMOLOLU - New Mexico State University|
|MARSALIS, MARK - New Mexico State University|
Submitted to: Agricultural and Environmental Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2018
Publication Date: 9/23/2018
Citation: Thapa, V.R., Ghimire, R., Mikha, M.M., Idowu, O., Marsalis, M. 2018. Land use effects on soil organic matter and wet aggregate stability in semiarid drylands. Agricultural and Environmental Letters. 3:180022. https://doi.org/10.2134/ael2018.05.0022.
Interpretive Summary: In the western region of the USA, there are approximately 336 million hectors of grassland cover. Maintaining soil quality and productivity of the grasslands are important in preserving soil from degradation and to protect soil surface layers from loss through erosion. The study was conducted at the New Mexico State University, Agricultural Science Center at Clovis, NM. The study evaluated the influence of ungrazed grassland (UGL), grazed grassland (GGL), and croplands with conventional tillage (CT), no-tillage (NT), and strip-tillage (ST) management on soil organic matter (SOM) components such as: (1) soil organic carbon (SOC); (2) particulate organic matter (POM); (3) potassium permanganate oxidizable carbon (POXC); (4) soil inorganic-N; and (5) wet aggregate stability (WAS). Results showed that grassland conserved SOM by approximately 37% more than cropland. The potassium permanganate oxidizable carbon (POXC) consider the labile fraction of SOC that can respond rapidly to management changes. In this study, the POXC:SOC ratio associated with ST was approximately 41% greater compared with the other land uses at the surface depth of 0-0.2 m. Soil inorganic-N was higher by approximately 270% in croplands than in grasslands. High soil inorganic-N was possibly due to fertilizer addition to the cropland. The manure addition through grazing required some time for soil inorganic-N to increase as the manure decomposes. The water stable macroaggregates were lower in CT treatment by approximately 23% than any other treatments in this study. The lower water stable macroaggregates associated with CT could be related to annual tillage practice that reduced the lifespan of soil macroaggregates and prevent soil macroaggregates formation and stabilization compared with less disturbed soil such as NT and grassland. In general, grasslands restoration and livestock integration could improve soil quality through improvements in SOM accumulation and soil structure stability.
Technical Abstract: Land uses may affect soil quality and nutrient cycling in the semiarid drylands. A study was conducted to evaluate soil organic matter (SOM) components, including soil organic carbon (SOC), particulate organic matter (POM), potassium permanganate oxidizable carbon (POXC), soil inorganic-N, and wet aggregate stability (WAS) under ungrazed grassland (UGL), grazed grassland (GGL), and croplands with conventional tillage (CT), no-tillage (NT), and strip-tillage (ST) management. Grasslands had 36.9% greater SOC content than croplands, while the POXC:SOC ratio was 41.2% greater in ST than the other land uses at 0-0.2 m depth. Soil inorganic-N was about 270% greater in croplands than in grasslands. The WAS in CT was 22.6% lower than all other managements. The SOC components and WAS did not vary significantly between land uses in 0.2-0.4 m depth. Restoring grasslands and livestock integration in croplands could improve soil quality through improvements in SOM accumulation and soil structure stability.