Two soil amendments, biochar and zeolites, were evaluated in their potential for increasing crop productivity and agro-system sustainability. The effect of biochar and zeolites, in combination with four nitrogen (N) rates [0 (N0), 50 (N50), 100 (N100), and 200 (N200) kg ha −1 ], on crop yield, N use efficiency, and soil properties was evaluated in a cropping system of irrigated forage maize ( Zea mays L.) grown in summer and oats ( Avena sativa L.) grown in winter as a catch crop. Biochar increased soil organic carbon (C), pH, cation exchange capacity (CEC), and extractable phosphorus (P), but strongly reduced N recovery in the set of the four cropping cycles. In biochar-amended plots, N50 had a negative apparent N recovery (− 21%), indicating that less N was recovered by the plants than in the N0 treatment without biochar. Biochar reduced maize dry matter (DM) yield by 15.6% in comparison to the untreated control, indicating N immobilization by biochar at low N rates (N0 and N50). Zeolites did not influence crop productivity or soil properties, except for the increase in extractable K, probably the result of its initial K content. N application to maize significantly increased the productivity of both crops, including that of the non-fertilized oats. Under the conditions of this experiment, biochar and zeolites did not prove to be useful soil amendments to increase crop DM yield in the short-term. The use of biochar increased soil organic C, which associated to a high N rate can enable the dual objective of maintaining productivity and the sustainability of the agro-system. The results stressed also the important role of oats as a cover crop to reduce the risk of nitrate leaching and denitrification during winter.

中文翻译：

---

应用生物炭和沸石后连续四季作物的氮素利用效率和作物产量

评估了两种土壤改良剂生物炭和沸石在提高作物生产力和农业系统可持续性方面的潜力。生物炭和沸石结合四种氮 (N) 比率 [0 (N0)、50 (N50)、100 (N100) 和 200 (N200) kg ha -1 ] 对作物产量、氮利用效率的影响，并在夏季种植的灌溉饲料玉米 (Zea mays L.) 和冬季种植的燕麦 (Avena sativa L.) 作为捕获作物的种植系统中评估土壤特性。生物炭增加了土壤有机碳 (C)、pH、阳离子交换容量 (CEC) 和可提取磷 (P)，但在四个种植周期的一组中显着降低了 N 回收。在生物炭修正的地块中，N50 的表观氮回收率为负 (- 21%)，表明植物回收的 N 比没有生物炭的 N0 处理少。与未处理的对照相比，生物炭使玉米干物质 (DM) 产量降低了 15.6%，表明生物炭在低氮率（N0 和 N50）下固定 N。沸石不影响作物生产力或土壤性质，除了可提取钾的增加，这可能是其初始钾含量的结果。玉米施氮显着提高了两种作物的生产力，包括未施肥燕麦的生产力。在该实验条件下，生物炭和沸石并未证明是短期内增加作物干物质产量的有用土壤改良剂。生物炭的使用增加了土壤有机碳，这与高氮率相关，可以实现保持生产力和农业系统可持续性的双重目标。