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- Title
Re-Evaluating Diagnostic Phosphorus Tests for Rice Systems Based on Soil Phosphorus Fractions and Field Level Budgets.
- Authors
Linquist, Bruce; Ruark, Matthew
- Abstract
The efficient management of P fertilizer in rice (Oryza sativa L.) systems is essential in ensuring optimal yields while also avoiding problems related to over application. Identifying P deficient soils is critical to developing efficient P recommendations. The objectives of study were to determine the extent of P deficiencies in California rice systems, evaluate diagnostic P tests, and identify soil P fractions that contribute to crop P nutrition. On-farm P-omission experiments were conducted at 64 sites where we measured Y-leaf P concentration, P uptake, and grain yield. Soil samples were collected and analyzed for Olsen and Bray-P as well as being subjected to a sequential P fractionation scheme to determine NaHCO3, NaOH, and HCl inorganic (Pi) and organic (Po) P. From grower interviews, an annual input/output P budget was constructed for each site that accounted for P fertilizer inputs and outputs (P removed at harvest) over the previous 5 yr. Olsen-P (critical value: 6 mg kg-1) and Y-leaf P tests (critical value: 0.2%) were reasonable at predicting P deficiencies across a wide range of soil types. The P budget, correlated with Olsen and Y-leaf P, was also helpful in determining if the grower applied P rates were adequate as the only P deficient sites had a P budget of 0.5 kg P ha-1 yr-1 or less. Sodium bicarbonate inorganic P (NaHCO3-Pi) , NaOH-, and HCl-Pi and -Po fractions were all correlated with Y-leaf P concentrations. The only Po fraction correlated with Y-leaf P and the P budget was HCl-Po. The primary sinks for excess applied P fertilizer were the NaHCO3-Pi and NaOH-Pi fractions.
- Subjects
CALIFORNIA; PLANTING; RICE; PHOSPHATE fertilizers; PLANT regulators; GROWTH regulators; AGRICULTURAL chemicals; FERTILIZERS
- Publication
Agronomy Journal, 2011, Vol 103, Issue 2, p501
- ISSN
0002-1962
- Publication type
Article
- DOI
10.2134/agronj2010.0365