State Key Laboratory of Grassland Agro-Ecosystems, Ministry lab, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu 730020, China.
State Key Laboratory of Grassland Agro-Ecosystems, Ministry lab, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu 730020, China.
Sci Total Environ. 2022 Jul 10;829:154628. doi: 10.1016/j.scitotenv.2022.154628. Epub 2022 Mar 16.
Forage crops are widely cultivated as livestock feed to relieve grazing pressure in agro-pastoral regions with arid climates. However, gaseous losses of soil nitrogen (N) following N fertilizer application have been considerable in response to the pursuit of increased crop yield. A two-year experiment was carried out in a typical saline field under a temperate continental arid climate to investigate the effect of N application rate on NO emissions from barley (Hordeum vulgare L.), corngrass (Zea mays × Zea Mexicana), rye (Secale cereale L.), and sorghum-sudangrass hybrid (Sorghum bicolor × Sorghum sudanense). The dynamics of NO emissions, hay yield, and crude protein (CP) yield were measured under four N application rates (0, 150, 200, and 250 kg ha) in 2016 and 2017. An NO emission peak was observed for all crop species five days after each N application. Cumulative NO fluxes in the growing season ranged from 0.66 to 2.40 kg ha and responded exponentially to N application rate. Emission factors of NO showed a linear increase with N application rate for all crop species, but the linear slopes significantly differed between barley or rye and corngrass and sorghum-sudangrass hybrid. The hay and CP yields of all forage grasses significantly increased with the increase of N application rate from 0 to 200 kg ha. Barley and rye with lower hay and CP yields showed higher NO emission intensities. The increased level of NO emission intensity was higher from 200 to 250 kg ha than from 150 to 200 kg ha. At N application rates of 200 and 250 kg ha, CP yield had a significantly negative correlation with cumulative NO emission and explained 50.5% and 62.9% of the variation, respectively. In conclusion, ~200 kg ha is the optimal N rate for forage crops to minimize NO emission while maintaining yield in continental arid regions.
在干旱气候的农牧区，广泛种植饲料作物以缓解放牧压力。然而，为了提高作物产量，氮肥施入后土壤氮（N）的气态损失相当可观。在温带大陆性干旱气候下的典型盐渍地进行了为期两年的实验，研究了氮肥施用量对大麦（Hordeum vulgare L.）、玉米草（Zea mays × Zea Mexicana）、黑麦（Secale cereale L.）和高粱-苏丹草杂种（Sorghum bicolor × Sorghum sudanense）NO 排放的影响。在 2016 年和 2017 年，在 4 个氮肥施用量（0、150、200 和 250 kg ha）下测量了 NO 排放、干草产量和粗蛋白（CP）产量的动态。所有作物种类在每次施氮后 5 天出现 NO 排放峰值。整个生长季的累积 NO 通量在 0.66 到 2.40 kg ha 之间，并随氮肥施用量呈指数增长。所有作物的 NO 排放因子随氮肥施用量呈线性增加，但大麦或黑麦与玉米草和高粱-苏丹草杂种之间的线性斜率差异显著。随着氮肥施用量从 0 增加到 200 kg ha，所有饲料草的干草和 CP 产量均显著增加。干草和 CP 产量较低的大麦和黑麦表现出较高的 NO 排放强度。从 200 增加到 250 kg ha 的 NO 排放强度增加水平高于从 150 增加到 200 kg ha。在 200 和 250 kg ha 的氮肥施用量下，CP 产量与累积 NO 排放呈显著负相关，分别解释了 50.5%和 62.9%的变异。综上所述，在大陆干旱地区，对于饲料作物而言，200 kg ha 左右的氮肥用量是最小化 NO 排放同时保持产量的最佳氮肥用量。
