Submitted to: Soil Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/16/2008
Publication Date: 7/15/2008
Citation: Guimaraes, M.F., Fonseca, I., Brossard, M., Portella, C., Brito, O.R., Ritchie, J.C. 2008. Monitoring changes in the chemical properties of an 2 oxisol under long-term no-tillage management in Sub3 Tropical Brazil. Soil Science. 173(6):408-416. Interpretive Summary: The rapid expansion of NT and minimum tillage systems replacing CT management systems in Brazil indicates that it is an economically acceptable management system for sub-tropical areas. However, there is a need of information about soil fertility at farmer's level. We used a set of data provided by a farmer on 16 fields with a history of NT management for a 10 year period to investigate how no-till impacted six basic fertility soil chemical determinations. Classification of the fields related to the mean values of different soil chemical properties showed changes in field classification related to management practice (lime addition, cropping sequence). Organic carbon in the NT soils was affected, particularly in the surface layer, mainly by the cropping sequence demonstrating the importance of the crops patterns in maintaining soil organic matter. This long-term study, which monitored soil chemical properties under NT management over a 10 year period, shows that it is possible to maintain good soil chemical properties under NT management under sub-tropical conditions. But the results stressed that short term and long-term culture rotation, including soybean, wheat, corn and oatmeal, need corrections via liming, and a rigorous fertilizer strategy.
Technical Abstract: In tropical areas soil chemical properties are most often studied in relationship to the type of tillage system. This paper presents data of the long-term effects of no-tillage (NT) management systems on the soil chemical properties of an Oxisol in sub-tropical Brazil. The study area was on a commercial farm where no-tillage systems had been adopted in 1978. Soil samples were collected annually from the 1983 to 1994 after winter crop harvest in 16 fields and at depths of 0.0-0.1m and 0.1-0.2m. Organic carbon, exchangeable calcium, magnesium, potassium, extractable phosphate and pH were measured. Soils were grouped by a Multivariate statistical agglomerative hierarchical method into five classes (I to V) based on statistical similarity to assess annual changes in soil chemical properties. This study shows that it is possible to maintain good soil chemical properties under operational NT systems in these sub-tropical conditions. This study also demonstrated the importance of sequence of crops for maintaining acceptable levels of soil organic matter and good soil chemical properties.