Fertilization & Nutrient Behavior
in Flooded Soils-75
 
 

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Project Leader and Principal UC Investigators

D.M. Brandon

L.A. Post

David R. Woodruff

J. Quick

Kenneth Nueller

J.F. Williams

W. Michael Canevari

C.M. Wick

G.J. St.Andre

 

This project, led by scientists in the UCD Department of Agronomy and Range Science, has the following aims:
  1. To determine the fertilizer requirements and crop management practices that will lead to full expression of the yield capacity and quality of improved rice genotypes.
  2. To evaluate the effect of plant type, plant population, and fertilizer interrelations on plant growth characteristics and yield performance.
  3. To determine the physiological response of the plant to various nutrient elements, organic acids, and gases produced in a flooded soil environment.
  4. To determine whether the critical nutrient values established for traditional California varieties are applicable to improved types.
  5. To investigate improved fertilization in connection with the changing technology of cultural management.
  6. To identify and ameliorate the factors in flooded soils which limit growth, development, yield, and quality.

SUMMARY OF CURRENT YEAR'S RESULTS:

  1. þ Fertilizer 15N banded or broadcast and incorporated by discing before flooding gave significantly higher yields than did split applications applied pre-flood and topdressed. High yields were not necessarily correlated with nitrogen use efficiency (see page 29 for details).
  2. þ Established and potential new varieties differ in growth and yield responses to temperature and nitrogen. Regional evaluation will be especially important for varieties containing indica germplasm.
  3. þ Rice straw incorporated just before flooding may cause nitrogen immobilization, with consequent nitrogen deficiency in seedlings. Organic acid and toxic gases can be problems if straw is incorporated into soil just before  flooding. They are usually avoided by incorporating straw 2-4 weeks before flooding.
  4. An Orange G colorimetric method of nitrogen plant analysis now being adopted by commercial laboratories speeds tissue testing and lowers the cost. Progress has been made in adapting the test for field use.
  5. Adding 2 lb actual zinc (2 .77 lb of ZnO) to 100 pounds of seed (applied with the seed fungicide or a proper sticker) assures that the maintenance zinc requirement will be met in rice grown on most zinc-deficient soils.
  6. Lime and high-pH-induced iron chlorosis can be corrected by fall applications and incorporation of from 1000 to 2000 pounds of sulfur per acre. Adjusting the soil surface to pH 7.0 will correct iron deficiency in most soils. Sulfuric acid applied directly on the soil surface just before flooding will give a similar response.

 

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