Fertilizer and irrigation management for selected forage grasses on Alaminos sandy clay

Abstract

Soils in pastures or grasslands in rolling to hilly areas are commonly strongly acidic and deficient in N, P and K-characteristics that are the major constraints to high herbage yield of forage for livestock production in these areas. These problems are aggravated by inadequate moisture supply especially at the onset of the dry season. The study quantified the fertilizer supplements and irrigation requirements for forage grasses on Alaminos sandy clay from October 1993 to April 1994 and October 1994 to April 1995. The first experiment on forage grass adaptability and relative importance of the macronutrients to local grass production showed that best yields in forage grasses Green timothy, Guinea and Splendid were obtained with fertilization of 120-90-120 (N-P2O5-K2O) rate. The degree of importance of N, P and K followed the order P>N>K. Yield reductions due to absence of P or N or K from the complete treatment were 78%, 62% and 11%, respectively. Splendid grass was more adapted to the local soil environment as seen in its higher relative DMY and large root biomass at low NPK level. With N fertilization, crude protein concentration increased from 7.28 to 10.59%. Higher P and K concentration was also obtained with application of these two elements. At 120 kg N per ha, pH decreased to 4.95, but its combination with 3.9 tons CaCO3 increased the pH significantly to 5.9. All plots with 90 kg P2O5/ha had P-test values greater than 18 ppm, except the limed plots. Exchangeable K increased, by increasing the rate of K up to 120 kg K2O/ha. The second experiment on nutrient and water use efficiency in Splendid grass showed that highest herbage yield was produced by fertilization with 120-90-120 (N-P2O5-K2O) rate and irrigation of 35.6 cm H2O. The macronutrient constraints followed the order P>N>K at the lowest irrigation level and N>P>K at the highest irrigation level. Efficiencies of N and P were higher at 60 kg N and 45 kg P2O5/ha while efficiency of K was lower than those observed for N and P. Water use efficiency was higher at 20.3 cm H2O. Although lower nutrient and water use efficiencies were obtained at higher nutrient and water levels, the herbage production per unit area was higher with these treatments. Soil moisture availability was close to field capacity at 20.3 and 35.6 cm H2O, and nearly approached permanent wilting point at the lowest irrigation treatment. Moisture removal was greater at 120-90-120 N-P2O5-K2O per ha rate compared to the 0-90-120, 120-0-90 and 120-90-0 treatments.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

145-157

Document Type

Article

Subject

Alaminos sandy clay, Fertilizer, Forage grasses, Irrigation

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