ISSN:
1435-0661
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
-1 soil test P (STP) levels. We conducted an experiment to investigate the hypothesis that seasonal changes in field conditions (especially soil moisture) along with the practice of air-drying soil samples prior to analysis may affect such correlations. Grass plots with a wide range of STP were randomly divided into two groups. In May (wet season), soil samples were taken from each plot in the first group, simulated rain was applied (75 mm h-1) to produce 30 min of runoff, and filtered runoff samples were analyzed for DRP. Each soil sample was analyzed for H2O content, sieved (2 mm), and split into two subsamples. One subsample from each plot was kept field-moist at4°C, and the other was air-dried. Phosphorus saturation was determined only on air-dry soil, but all soil subsamples were analyzed by Mehlich III and distilled H2O methods. In August (dry season), the second group of plots received the same treatment. All correlations of STP to runoff DRP were significant (P 〈 0.01), regardless of season or STP method. Water-extractable STP from air-dry soil (mean = 28.5 mg kg-1) and Mehlich III STP (mean = 145 mg kg-1) were not affected by season, but DRP concentration in August runoff (mean = 1.05 mg L-1) was almost double that in May (mean = .057 mg L-1), so the resulting correlations were affected. Water-extractable STP from field-moist soil was higher in August (mean = 23 mg kg-1) than in May (mean = 16 mg kg-1), and P saturation levels showed a similar trend. Runoff volumes were smaller in August, so season had little effect on mean DRP-mass loss.
Type of Medium:
Electronic Resource
