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首页> 外文期刊>Agroforestry Systems >Phosphorus pools in Oxisols under shaded and unshaded coffee systems on farmers' fields in Brazil
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Phosphorus pools in Oxisols under shaded and unshaded coffee systems on farmers' fields in Brazil

机译：巴西农民田间有阴影和无阴影咖啡系统下的Oxisols中的磷池

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Phosphorus (P) is a primary limiting nutrient for crop production in weathered tropical soils. The deficiency is mainly caused by sorption of phosphate onto Al- and Fe- (hydr)oxides. We hypothesise that the distribution of soil P among various pools is influenced by land use. Our objective was to characterise the soil inorganic (Pi) and organic P (Po) pools and to compare the various pools at different depths in agroforestry (shaded) and monocultural (unshaded) coffee cultivation systems. The study was carried out in the Atlantic Coastal Rainforest domain, Brazil, with Oxisols as the dominant soil type. Soils were collected from four farmers' coffee (Coffea arabica L.) fields, two agroforestry and two monocultural systems. Three profiles were sampled per field, at depths of 2–3, 10–15 and 40–60 cm. A simplified sequential P fractionation was carried out, using resin, 0.5 M NaHCO3, 0.1 M NaOH, 1 M HCl and concentrated HCl as extractants. Sum-P (resin, NaHCO3 NaOH, 1 M HCl and concentrated HCl) ranged from 370 to 830 mg kg−1. Concentrated HCl extracted the largest portion (74%), followed by NaOH (22.5%). Labile (sum of resin, NaHCO3 and NaOH) P ranged from 13 to 40% of Sum-P. The major part (62%) of the labile fraction was Po. In the agroforestry fields, the amount of Po decreased less with depth and the percentage of Po in labile pools was higher than in monocultural fields. This suggests that agroforestry maintains larger fractions of P available to agricultural crops by influencing the dynamics of P through the conversion of part of the Pi into Po, thereby reducing P losses to the unavailable pools.
机译：磷是风化热带土壤中作物生产的主要限制养分。该缺陷主要是由于磷酸盐吸附在Al和Fe-（氢）氧化物上。我们假设土壤磷在各个水池之间的分布受土地利用的影响。我们的目标是表征土壤无机（Pi）和有机磷（Po）池，并比较农林业（阴影）和单文化（无阴影）咖啡种植系统中不同深度的各种池。这项研究是在巴西的大西洋沿岸雨林地区进行的，土壤中的主要土壤污染物为Oxisols。从四个农民咖啡田（Coffea arabica L.），两个农林业和两个单一文化系统中收集土壤。每个场在2-3 cm，10-15和40-60 cm的深度采样了三个剖面。使用树脂，0.5 M NaHCO3 ，0.1 M NaOH，1 M HCl和浓HCl作为萃取剂，进行了简化的连续P分馏。 Sum-P（树脂，NaHCO3 NaOH，1 M HCl和浓HCl）的范围为370至830 mg kg-1 。浓HCl提取量最大（74％），其次是NaOH（22.5％）。不稳定（树​​脂，NaHCO3 和NaOH的总和）的P占Sum-P的13％至40％。不稳定部分的主要部分（62％）是Po。在农林业领域中，Po的含量随深度的减少而减少，不稳定池中Po的百分比高于单一栽培领域。这表明，农林业通过将部分Pi转化为Po来影响P的动力学，从而保持了P的大部分可用于农作物，从而减少了P损失到不可用的库中。

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