东北三省典型春玉米土壤剖面氮库变化及平衡特征

【目的】研究了东北三省典型春玉米种植区在0—90 cm土壤剖面土壤氮素的变化及平衡特征,试图了解东北三省典型春玉米种植区传统农民习惯施肥措施下土壤氮素的固持潜力。【方法】于2012年春玉米全生育期定点跟踪了黑龙江、吉林和辽宁省各17户,总计51户农民习惯处理,测定了0—30、30—60、60—90 cm土层中全氮(TN)、矿质氮(NO3-N、NH4-N)、颗粒有机氮(PON)、微生物生物量氮(SMBN)和可溶性有机氮(DON)以及春玉米产量,并计算了春玉米播种前和收获后的氮素平衡。【结果】黑龙江、吉林、辽宁典型春玉米种植区0—90 cm整个土壤剖面TN储量分别为357.9、286.9、218.1 kg·hm~(-2),且各省土壤TN储量平均值均达显著性水平(P0.05)。黑龙江、吉林、辽宁0—30 cm表层土壤TN含量平均值分别为1.4、1.0、0.7 g·kg~(-1),且各省TN含量均达显著性水平(P0.05);在30—60 cm、60—90 cm土层TN含量平均值分别为0.9、0.6、0.4 g·kg~(-1)和0.6、0.4、0.3 g·kg~(-1),黑龙江各土层土壤剖面TN含量平均值显著高于辽宁(P0.05)。0—30 cm土层中,随着纬度的降低,黑龙江、吉林、辽宁三省PON、PON/TN、SMBN/TN呈增加趋势,而SMBN含量则呈降低趋势,PON、PON/TN和SMBN含量平均值三省间均达显著水平(P0.05),黑龙江与辽宁SMBN/TN平均值达显著水平(P0.05);在30—60 cm土层,黑龙江、吉林和辽宁PON/TN随着纬度的降低而升高,且三省间PON/TN平均值达显著水平(P0.05),黑龙江PON显著低于吉林、辽宁两省(P0.05),黑龙江DON显著高于吉林和辽宁,吉林DON/TN平均值显著低于辽宁(P0.05);在60—90 cm土层,吉林SMBN、SMBN/TN的平均值显著高于黑龙江、辽宁(P0.05),黑龙江DON/TN平均值显著低于吉林、辽宁(P0.05)。各省土壤全氮及各活性氮库随着土层深度的增加总体呈下降趋势。0—30 cm土层,辽宁NO_3-N含量平均值显著低于黑龙江、吉林(P0.05);在30—60 cm、60—90 cm土层吉林NO3-N含量平均值显著高于黑龙江、辽宁(P0.05)。吉林施肥量最高,因此吉林氮素平衡显著高于黑龙江、辽宁(P0.05),且吉林表现为氮素盈余,黑龙江和辽宁基本上处于氮素平衡状态。2012年黑龙江、吉林、辽宁玉米产量平均值分别为11.9、11.3和10.8 t·hm~(-2),黑龙江玉米产量显著高于吉林、辽宁(P0.05)。【结论】东北三省间土壤活性氮库消长规律与土壤全氮并不完全一致,东北三省产量维持在11 t·hm~(-2)左右,吉林省典型春玉米种植区氮素危害环境的风险较大。

Characteristics of Nitrogen Pools and Nitrogen Balance in Soil Profile in Typical Spring Maize Planted Regions in Northeast China

【Objective】The characteristics of nitrogen pools in 0-90 cm soil depth and the nitrogen balance was elucidated to make clear the potential of nitrogen immobilization under the current farmers’ fertilizer practices in typical spring maize planted in northeastern China.【Method】Seventeen sites in each of the provinces of Heilongjiang, Jilin, and Liaoning, adding up to 51 sites, were observed on the farmer’s agricultural systems during the whole growth period of spring maize in the year of 2012. The soil total nitrogen (TN), mineral nitrogen (NO₃-N, NH₄-N), particulate organic nitrogen (PON), microbial biomass nitrogen (SMBN), and dissolved organic nitrogen (DON) in 0-30, 30-60, 60-90 cm soil depth and spring maize yield were determined, and nitrogen balance between before the maize was sown and after the maize was harvested was calculated.【Result】The TN stock of 0-90 cm soil depth in Heilongjiang, Jilin, and Liaoning was 357.9, 286.9, and 218.1 kg·hm^-2 respectively in typical spring maize planted in northeastern China. The mean of TN stock in each province was significant (P＜0.05). In 0-30 cm soil depth, the mean of TN concentration in Heilongjiang, Jilin, and Liaoning province was 1.4, 1.0, 0.7 g·kg^-1, respectively; moreover, the mean of TN concentration in each province was significant (P＜0.05). In 30-60 cm or 60-90 cm soil depth, the mean of TN concentration in Heilongjiang, Jilin, and Liaoning provinces were 0.9, 0.6, 0.4 g·kg^-1and 0.6, 0.4, 0.3 g·kg^-1, respectively, and in either soil depth, the mean of TN concentration in Heilongjiang was significantly (P＜0.05) higher than that in Liaoning. In 0-30 soil depth, the difference of the mean of PON concentration, PON/TN, SMBN/TN among Heilongjiang, Jilin, and Liaoning provinces increased and SMBN concentration decreased as latitude decreased, and the difference of the mean of PON concentration, PON/TN, or SMBN concentrations at each province was significant (P＜0.05) respectively. The difference of the mean of SMBN/TN between Heilongjiang and Liaoning provinces was significant (P＜0.05). In 30-60 cm soil depth, the mean of PON/TN among Heilongjiang, Jilin, and Liaoning provinces increased as latitude decreased, and the difference of the mean of PON/TN at each province was significant (P＜0.05). The mean of PON concentration in Heilongjiang province was significantly (P＜0.05) lower than that in Jilin or Liaoning province, and the mean of DON concentration in Heilongjiang province was significantly (P＜0.05) higher than that in the other two provinces. The mean of DON/TN in Jilin province was significantly (P＜0.05) lower than that in Liaoning province. In 60-90 cm soil depth, the mean of SMBN or SMBN/TN in Jilin province was significantly (P＜0.05) higher than that in Heilongjiang and Liaoning provinces, and the mean of DON/TN in Heilongjiang was significantly (P＜0.05) lower than that in Jilin or Liaoning provinces. On the whole, total nitrogen and soil active nitrogen pools at each province decreased as the soil depth increased. The mean of NO₃-N in Liaoning province in 0-30 cm soil depth was significantly lower than that in Heilongjiang or Jilin province, and the mean of NH₄-N in Heilongjiang and Jilin was significant (P＜0.05). The mean of NO₃-N in Jilin province in 30-60 cm or 60-90 cm soil depth was significantly (P＜0.05) higher than that in Heilongjiang or Liaoning province. Because of the highest nitrogen rate in Jilin province among the three provinces, nitrogen balance in Jilin province was significantly (P＜0.05) higher than the other two provinces, and Jilin province showed N surplus, while Heilongjiang and Liaoning province showed a balanced N on the whole. In the year of 2012, the mean of the yield of maize in Heilongjiang, Jilin, and Liaoning provinces was at 11.9, 11.3 and 10.8 t·hm^-2 respectively, and the average yield in Heilongjiang province was significantly higher than the other two provinces.【Conclusion】 There wasn’t completely consistency in the increased or decreased trend between total nitrogen and soil active nitrogen pools among Heilongjiang, Jilin, and Liaoning provinces; the yield maintained 11.0 t·hm^-2 in northeastern China on the whole, and the negative environmental effect of nitrogen in the spring maize planted region in Jilin province was relatively higher than the other two provinces.