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Nutrient Leaching in Oxisols Under Native and Managed Vegetation in Brazil
Author(s) -
Wilcke Wolfgang,
Lilienfein Juliane
Publication year - 2005
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2004.0350
Subject(s) - oxisol , leaching (pedology) , nutrient , pasture , agronomy , environmental science , chemistry , soil water , soil horizon , soil science , biology , organic chemistry
Brazilian savanna Oxisols are prone to nutrient leaching because of low nutrient retention and high water conductivity. We determined downward and upward fluxes of Ca, Mg, K, NH 4 –N, and NO 3 –N at 0.3‐, 0.8‐, and 2.0‐m soil depths under native savanna vegetation (Cerrado), Pinus caribaea Morelet plantation, managed productive Brachiaria decumbens Stapf pasture, degraded B. decumbens pasture, conventional tillage, and no‐till corn ( Zea mays L.)–soybean [ Glycine max (L.) Merr.] cropping using exchange resin cores, and set up a nutrient budget using previously published input data. At each of the study depths, we installed three to six PVC tubes (0.10 m in diameter, 0.11 m in length) filled with a mixture of field‐fresh soil and HBr‐washed ion exchange resin (Amberlite MB‐20, 10:1 v/v), which were removed and extracted after 2 yr. Downward fluxes at 2‐m soil depth ranged from 0.22 to 2.3 g Ca, 0.02 to 0.71 g Mg, 0.08 to 1.17 g K, not detected (n.d.) to 0.96 g NH 4 –N, and n.d. to 4.4 g NO 3 –N m −2 yr −1 Upward fluxes, because of capillary rise, frequently amounted to 30 to 50% of downward fluxes. At 0.3‐m depth, net leaching fluxes of Ca in the cropping systems and productive pasture (2.3–4.9 g m −2 yr −1 ) and of K and NO 3 –N in the cropping systems (K: 0.73–0.85, NO 3 –N: 2.3) were significantly higher than in all other systems except for NO 3 –N in Pinus (Ca: 0.02–0.18, K: 0.09–0.15; NO 3 –N: n.d.–0.70). In forests and pastures, all nutrients accumulated on balance while in cropping systems budgets were balanced or negative except for N. To reduce these losses, timing of fertilizer amendments should be optimized and in the no‐till system evaporation and fast water fluxes reduced for example, by stubble mulching.