Скачать или смотреть Drawdown of soil phosphorus by crop removal: A meta-analysis of fields with halted fertilization

Title: Drawdown of soil phosphorus by crop removal: A meta-analysis of fields with halted fertilization


Presenter: Dr. Luciano (Luke) Gatiboni, Associate Professor and Soil Fertility Extension Specialist, North Carolina State University


Description: Drawdown of soil phosphorus by crop removal: A meta-analysis of 56 fields with halted fertilization. Phosphorus is an essential nutrient for plants and is commonly applied as fertilizer in agricultural fields. However, excessive fertilization builds up soil P, increasing its potential to cause environmental pollution. Cropping without phosphorus fertilization is one of the few options to reduce soil test P. The objective of this study was to evaluate the average P drawdown rate presented in research publications. We selected 56 sites presented in 14 publications that included at least 3 years of cultivation without P fertilization and had soil test P (STP) analyzed by Mehlich-1, Mehlich-3, Olsen, or Bray at the beginning of the drawdown study and at regular times during the drawdown regime. A preliminary bootstrap of decision tree analysis identified the initial STP as the most important predictor of the drawdown rate. All data was converted to Mehlich 3 P equivalent using the conversion factors developed by IPNI. A bootstrap analysis with 5,000 resamplings was used to compare the annual drawdown rate in fields grouped by four initial Mehlich 3 P equivalent classes: 6−28, 29−66, 67-115, and 115−261 mg kg-1. The annual P drawdown rate in the first 15 years of the drawdown regime was respectively 1.21, 2.88, 5.08, and 8.98 mg kg-1 yr-1.


Time: Tuesday June 25th at 11am CST


*1 Nutrient Management CEU *