ABSTRACT
The development of high-yielding soybean has led to a substantial increase in the area under cultivation in many parts of Brazil, mainly in the Cerrado (savanna); nevertheless, one of the major constraints for crop production in those areas is that Cerrado soils are quite deficient in phosphorus (P). Studies have confirmed that 65.1% of all tropical soils are strongly deficient in P, whereas 26.6% are moderately deficient. The experimental soil was classified as Typic Quartzipsamment under the USDA soil taxonomy. Typic Quartzipsamment soils are very permeable and have low carbon content, poor water retention, and low levels of fertility and available P. Plant samples were acid-digested at University of California at Riverside using a CEM Mars 5 microwave system that is capable of monitoring both temperature and pressure of a representative sample during digestion.
