Soil Acidity Amelioration Impact in a No-till System in West Tennessee – USA Differs By Cover Crop Type and Nitrogen Application Rate.

Soil acidity amelioration impact in a no-till system in west Tennessee – USA differs by cover crop type and nitrogen application rate

 

Moniki Campos Janegitz¹, Sean Michael Schaeffer², Virginia L. Jin³, Ciro Antonio Rosolem¹, Lidong Li²

¹São Paulo State University, College of Agricultural Sciences, Botucatu-SP/Brazil

²University of Tennessee, Biosystems Engineering and Soil Science, Knoxville –TN/ USA

³USDA-Agricultural Research Service Lincoln,-NE/USA

Conservation soil management practices may influence the soil acidity. Surface application of limestone may be required in no-till systems is to ameliorate soil acidity and to achieve high yields. The application of lime may also increase microbial activity on soil. Specifically, the microbial activity of soil can be determined by C-loss via respiration. We evaluated microbial respiration after lime was applied to no-till cotton fields that have been under different agriculture practices for 31 years. Treatments consisted of: lime and no lime, nitrogen fertilizer rate application (0, 36, 72 e 108 kg ha^-1) and cover crop (no cover, vetch and wheat). Soil samples were collected in Spring, 2014 from 0 to 10 cm depth. We neutralized soil acidity using a pH buffer procedure to calculate doses for each plot. Soil samples were incubated at 25 º C in a laboratory conditions, and respiration was then measured at 0, 1, 3, 7 and 14 days after liming using an infrared gas analyzer (IRGA, LICOR-820). We found high fertilization rates and legume cover crops caused acidity in soil. Soil respiration was significantly higher in the higher in limed compared to un-limed soils. However, after lime was used in the treatments with vetch cultivation, it was observed that there was higher respiration rate regardless of the use of nitrogen. The pH data was correlated with respiration data; in the treatment with low pH, respiration rate was also low. Though some CO₂ measured as respiration likely came from added lime, the observed increases in respiration were above that expected from a purely inorganic CO₂-source.

Acknowledgement: Capes, University of Tennessee, USDA e FAPESP – Proc 2012/09550-0