عنوان

Cation movement and management in an Indonesian ultisol

TLpq303972957

انگلیسی

Cation movement and management in an Indonesian ultisol

[Thesis]

T. S. Dierolf

R. Yost

University of Hawai'i at Manoa

1992

221

Ph.D.

University of Hawai'i at Manoa

1992

Minimizing soil nutrient losses is a way of increasing the use efficiency of soil amendments and can reduce both production costs and environmental costs. By understanding the fate of nutrients contained in soil amendments, management practices that minimize nutrient losses can be developed. Thus, cation losses, through leaching and vegetation removal, from a clayey Indonesian Typic Kanhapludult were quantified. Water flow was characterized by the internal drainage method. An initial rapid phase of drainage (67% of a 7.25 cm water application passed below the 112.5-cm depth within the 100 minute irrigation period) was followed by a slow phase. Sharp breaks in the drainage curves separated the phases and provided estimates of the macropore (rapid phase) and micropore volumes (slow phase). Two hypotheses, developed from the characterization of water flow, were that surface applied cations are susceptible to rapid leaching loss and that subsoil accumulation of cations would be difficult. In one field experiment, essentially all of the K (100 kg K ha was applied as KCl fertilizer) was recovered after irrigating with 9.1 cm of water. However, mass balance calculations for another experiment (six crops grown during 2 years) indicated that up to 285 kg K ha (600 kg K ha was applied) was not recovered and presumed to have leached below the 90-cm depth. Thus, cation leaching is more likely to occur because of the cumulative effect of rainfall (688 cm during the 2-year experiment) rather than for "individual, large storm events". For one treatment in the 2-year experiment, only 5 kg K and 130 kg Ca ha accumulated between 30-90 cm, while 285 kg K and 263 kg Ca ha were calculated to have leached below the 90-cm depth. These results indicated that the majority of cations in draining water did not accumulate in the subsoil. Returning the straw/stover resulted in optimal grain yields for all six crops when 70 kg K ha was applied initially. Removing the straw/stover, for the same amount of K, resulted in yield decreases by the fourth crop. Only moderate amounts of K are required for cowpea, rice, and soybean production as long as the straw/stover is returned evenly over the harvest area.

Agronomy

Biological sciences

Indonesia

soybean

R. Yost

T. S. Dierolf

p

[Thesis]

276903

a

Y