Nutrient accumulation, export and cycling in Jatropha curcas L .

ABSTRACT The knowledge concerning nutrient accumulation rate allows defining the best amount and most appropriate time for its supply. Estimating nutrient amount in the aerial part of the plants is particularly important to species such as Jatropha curcas L., since there are no consistent calibration studies to indicate the amount of fertilizer to be applied. The objective of this study was to evaluate nutrient accumulation, export and cycling in Jatropha curcas. The experiment was carried out in Cassilândia, state of Mato Grosso do Sul, Brazil, during 52 months in a completely randomized design, with four replications and fifteen treatments, which consisted of different evaluation times. A large variation in the amount of nutrients accumulated in leaves was found due to senescence and leaf abscission in the driest and/or coldest period of the year. Nutrient accumulation in the aerial part is relatively low in the first 22 months. To meet Jatropha curcas requirements, fertilization during the first two years must provide 40; 50; 50; 21; 16; 5; 0.7; 0.3; 4; 8 and 1 kg ha-1 of N, P2O5, K2O, Ca, Mg, S, B, Cu, Fe, Mn and Zn, respectively. From the third year of cultivation, topdressing fertilization should restitute 40, 110, 55 and 3 kg ha-1 of N, P2O5, K2O and S, respectively. To replace the exported amount of nutrients, it should be supplied more 50, 100, 30 and 3 kg ha-1 of N, P2O5, K2O and S, respectively, per ton of grain to be produced.

摘要
了解养分累积速率，可明确作物养分供给的最优用量与最佳时机。针对麻疯树（Jatropha curcas L.）这类作物，估算其地上部养分含量尤为关键，因目前尚无统一的校准研究可指导合理施肥量。本研究旨在探究麻疯树的养分累积、携出与循环特征。本试验于巴西南马托格罗索州的卡西兰迪亚（Cassilândia）开展，时长52个月，采用完全随机设计，设置4次重复与15个处理，各处理以不同的评估采样时段为变量。研究发现，在年度最干旱与/或最冷时段，因叶片衰老与脱落，叶片累积的养分量存在显著波动。种植前22个月，麻疯树地上部的养分累积量相对较低。为满足麻疯树的养分需求，种植前两年的施肥需分别施入氮（N）、五氧化二磷（P₂O₅）、氧化钾（K₂O）、钙（Ca）、镁（Mg）、硫（S）、硼（B）、铜（Cu）、铁（Fe）、锰（Mn）与锌（Zn），用量依次为40、50、50、21、16、5、0.7、0.3、4、8与1 kg·ha⁻¹。种植第三年起，追肥需分别返还氮、五氧化二磷、氧化钾与硫，用量依次为40、110、55与3 kg·ha⁻¹。若要弥补籽粒携出的养分量，每生产1吨籽粒需额外施入氮、五氧化二磷、氧化钾与硫，用量依次为50、100、30与3 kg·ha⁻¹。