Mehmood Khalid, Li Jiu-Yu, Jiang Jun, Shi Ren-Yong, Liu Zhao-Dong, Xu Ren-Kou
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2017 Mar;24(7):6698-6709. doi: 10.1007/s11356-017-8373-2. Epub 2017 Jan 13.
The rapid increase in agricultural pollution demands judicious use of inputs and outputs for sustainable crop production. Crop straws were pyrolyzed under oxygen-limited conditions at 400 °C for 2 h to prepare peanut straw biochar (PB), canola straw biochar (CB), and wheat straw biochar (WB). Then, 300-g soils were incubated each with urea nitrogen (UN) and UN + biochars with or without dicyandiamide (DCD) for 60 days. During the incubations, soil acidification induced by urea was somewhat inhibited by biochars, but nitrification of hydrolyzed NH produced much more acidity than the neutralization potential of the biochars. In single UN (200 mg/kg) treatment, soil pH decreased drastically and the final pH after incubation was lower than the control. Antagonistic to UN, all three biochars neutralized the soil acidity, which was consistent to their inherent alkalinity. DCD inhibited nitrification which was obvious throughout the incubations, as 30 mg/kg DCD + 200 mg/kg UN combined with 1 % PB, CB, and WB retained 0.94, 0.79, and 1.19 units higher pH, respectively, and significantly reduced exchangeable acidity over the treatments without DCD (P < 0.05). The treatments of UN + biochars with and without DCD had highly significant effects on soil pH, exchangeable Al, NH-N, (NO+NO)-N, and available P (P < 0.05). Amplified NH-N retentions at higher rates of PB referred increased negatively charged sites for nutrient adsorptions. Applied UN transformations varied among different treatments, and the maximum amounts of total mineral N recovered were 218.3, 218.5, and 223.8 mg/kg in the presence of DCD by PB, CB, and WB, compared to 198.2, 201.6, and 205.2 mg/kg, respectively, in no DCD treatments. Urea induced severe soil acidification and even lowered the ameliorative effects of applied biochars. Thus, ammonium-based fertilizers must include nitrification inhibitor (DCD) and, if used in combination with biochars will offer a suitable choice to reduce the acidity, improve base saturation and fertility of soil for sustainable agriculture.
农业污染的迅速增加要求明智地使用投入和产出以实现可持续作物生产。将作物秸秆在400℃的限氧条件下热解2小时，以制备花生秸秆生物炭（PB）、油菜秸秆生物炭（CB）和小麦秸秆生物炭（WB）。然后，将300克土壤分别与尿素氮（UN）以及添加或不添加双氰胺（DCD）的UN + 生物炭一起培养60天。在培养过程中，生物炭对尿素引起的土壤酸化有一定的抑制作用，但水解产生的NH的硝化作用产生的酸度比生物炭的中和潜力大得多。在单一UN（200毫克/千克）处理中，土壤pH值急剧下降，培养后的最终pH值低于对照。与UN相反，所有三种生物炭都中和了土壤酸度，这与其固有碱度一致。DCD抑制硝化作用在整个培养过程中都很明显，因为30毫克/千克DCD + 200毫克/千克UN与1%的PB、CB和WB组合分别使pH值比不添加DCD的处理高0.94、0.79和1.19个单位，并显著降低了交换性酸度（P < 0.05）。添加和不添加DCD的UN + 生物炭处理对土壤pH值、交换性铝、NH-N、（NO+NO）-N和有效磷有极显著影响（P < 0.05）。较高PB施用量下NH-N保留量的增加表明用于养分吸附的负电荷位点增加。施用的UN转化在不同处理之间有所不同，在添加DCD的情况下，PB、CB和WB处理中回收的总矿质氮的最大量分别为218.3、218.5和223.8毫克/千克，而在不添加DCD的处理中分别为198.2、201.6和205.2毫克/千克。尿素导致严重的土壤酸化，甚至降低了施用生物炭的改良效果。因此，铵基肥料必须包括硝化抑制剂（DCD），如果与生物炭结合使用，将为减少土壤酸度、提高碱饱和度和肥力以实现可持续农业提供合适的选择。
