锌源和施锌方法对石灰性土壤锌组分及锌肥利用率的影响

【目的】选用合适的锌肥以及合理的施肥方式不仅可以提高小麦籽粒锌营养品质,还可以提高石灰性土壤的锌肥利用率。因此,研究不同锌源和施肥方式对石灰性土壤中锌组分含量以及锌肥利用率的影响具有重要意义。【方法】采用盆栽试验,设置两种锌源(水溶态锌肥Zn SO4·7H2O和螯合态锌肥Zn-EDTA)全层混匀均施和表面条施两种方式,调查了土壤中交换态Zn(Ex-Zn)、松结有机态Zn(LOM-Zn)、碳酸盐结合态Zn(Carb-Zn)、氧化锰结合态Zn(Ox Mn-Zn)、紧结有机态Zn(TOM-Zn)5种形态锌的含量,分析了小麦对锌肥的利用率。【结果】全层混匀均施与表面条施,两种锌肥均增加了小麦籽粒和秸秆Zn含量,全层均施Zn SO4·7H2O处理的籽粒Zn含量比对照提高43%,均施和表面条施Zn-EDTA的籽粒Zn含量分别比对照提高57%和75%;Zn-EDTA均施和条施的锌肥利用率分别为6.5%和5.3%,Zn SO4·7H2O均施和条施的锌肥利用率分别为3.6%和1.3%。小麦收获后,条施Zn SO4·7H2O和Zn-EDTA的施锌区有效锌含量分别为9.25和1.97 mg/kg,分别为均施处理的2倍和1.8倍;与对照相比,Zn SO4·7H2O和Zn-EDTA条施及均施的4个处理均增加了土壤中各形态锌的含量,并且4个处理与对照土壤中各形态Zn含量的规律一致,即:松结有机态碳酸盐结合态紧结有机态氧化锰结合态交换态。均施Zn SO4·7H2O和Zn-EDTA 2个处理的交换态Zn含量分别为0.12和0.13 mg/kg,条施分别为0.38和0.54 mg/kg;均施处理松结有机态Zn含量分别为5.26和1.56 mg/kg;不同处理碳酸盐结合态Zn含量变化趋势与松结有机态Zn含量基本一致;条施Zn SO4·7H2O施肥区氧化锰结合态Zn含量为对照的4倍,不同处理的土壤中紧结有机态Zn含量变化规律与氧化锰结合态Zn含量变化规律相似。相关分析表明,土壤交换态Zn、松结有机态Zn和碳酸盐结合态Zn含量均与有效锌含量呈显著正相关关系,与不施锌肥相比,Zn-EDTA施入土壤后,小麦收获后松结有机态Zn和碳酸盐结合态Zn含量明显增加,而紧结有机态Zn则相对减少。【结论】潜在缺锌石灰性土壤上施用螯合态锌肥Zn-EDTA能显著增加土壤中潜在有效的锌组分以及锌肥利用率,而且施用螯合态锌肥后,较高的有效锌含量可以维持至小麦收获后,有效提高了锌肥利用率。与均施处理相比,条施这种集中施用的施肥方法可以增加近根系土壤中有效性较高的锌形态含量。

Effects of Zn sources and application methods on the contents of various Zn fractions and Zn fertilizer utilization efficiency

【Objectives】Proper sources and application methods of Zn can improve grain Zn nutritional quality and Zn utilization efficiency. Therefore, the effect of two Zn fertilizers and two application methods on Zn fractions and Zn use efficiency were investigated in potentially Zn-deficient calcareous soil.【Methods】 A greenhouse pot experiment with two Zn sources(Zn-EDTA and ZnSO4·7H2O)and two application methods(mixed with whole soil in a pot, and top dressed in 3 cm wide banding below wheat)experiment was conducted. The contents of five different Zn fractions were analyzed, and the Zn fertilizer efficiency of wheat was calculated.【Results】 Both Zn-EDTA and ZnSO4·7H2O increased the grain and straw Zn concentration. The grain Zn concentration was increased by 43% in the mixed ZnSO4·7H2O application, and by 57% and 75% in the mixed and banded Zn-EDTA applications, respectively. The Zn utilization efficiency was 6.5% and 5.3% in the mixed and banded Zn-EDTA applications, 3.6% and 1.3% in the mixed and banded ZnSO4·7H2O applications. After harvest, the soil available Zn were 9.25 mg/kg and 1.97 mg/kg with banded application of Zn-EDTA and ZnSO4·7H2O, which were 2 and 1.8 times of those with the mixed applications. Both ZnSO4·7H2O and Zn-EDTA increased the contents of all the five Zn fractions, which were all in the order of loose organic matter Zn(LOM-Zn) carbonate bonded Zn(Carb-Zn) tight organic matter bound Zn(TOM-Zn) manganese oxide bound Zn(OxMn-Zn) exchangeable Zn(Ex-Zn). The exchangeable Zn concentration of the mixed ZnSO4 and Zn-EDTA applications were 0.12 and 0.13 mg/kg, respectively. The LOM-Zn concentration of banded ZnSO4·7H2O and Zn-EDTA applications were respectively 5.26 and 1.56 mg/kg. The trends for carbonate-Zn and loose organic matter-Zn concentrations in the mixed and banded ZnSO4·7H2O applications were similar. Manganese oxide bound Zn concentration with the banded Zn application was 4 times of that in the control. The soil available Zn concentrations were positively correlated with the Ex-Zn, LOM-Zn and Carb-Zn concentrations. Compared to no Zn application, the concentrations of LOM-Zn and Carb-Zn were significantly increased, while that of TOM-Zn was decreased with the application of Zn-EDTA. 【Conclusions】 In the potentially Zn-deficient calcareous soil, the application of Zn-EDTA could increase the contents of potentially available Zn and the Zn utilization efficiency, and there was higher available Zn concentration to sustain plant available Zn until wheat harvest after the application of chelating Zn fertilizer. Thus, it increased Zn utilization efficiency. The banded application treatments produced the higher available Zn fractions near the wheat roots than the mixed application treatments. Key words: calcareous soil; Zn fertilizer; Zn fertilizer application methods; Zn fractions; Zn fertilizer utilization efficiency; wheat