长期施氮磷化肥对不同种植体系土壤交换性钙分布与累积的影响

Effect of long-term NP chemical fertilization on soil exchangeable Ca distribution and accumulation with different cropping systems in the Loess Plateau

以22年定位试验为基础，研究了长期施用氮磷化肥(NP)下不同种植体系土壤交换性钙在剖面上分布与累积状况。结果表明：研究区为石灰性土壤，交换性钙含量较高；不同种植体系交换性钙在土壤剖面上发生淋溶累积现象，在140～180 cm土层产生累积峰，累积峰值：玉米一小麦(2a)+糜子轮作为13 180 ms／kg、豌豆一小麦(2a)+糜子轮作为12 597 mg／kg、红豆草一小麦(2a)轮作为11 960 mg／kg、豌豆一小麦(2a)+玉米轮为11 778 mg／kg、小麦连作为11 590 mg／kg、小麦(2a)+糜子一玉米轮作为11 290 mg／kg；不同种植体系0～200 CII1土壤交换性钙的总累积量以玉米一小麦(2a)+糜子轮作最高，为269．67 t／hm2，小麦连作最低，为218．78 t／hm2。不同种植体系交换性钙在土壤剖面上分布不同主要是由作物和种植方式不同引起，不同种植体系0～200 cm土壤交换性钙的总累积量差异不显著。

Based on long-time location experiments, the changing condition of exchangeable Ca in soil profiles of different cropping systems under the condition of 22 years＇ continuous application of NP chemical fertilizer in the Loess Plateau was studied. The results show that the content of exchangeable Ca is high because of research area was calcareous soil. The eluviation and accumulation of exchangeable Ca occur in soil profiles. The peak is at 140 - 180 cm soil depth with the values of 13 180, 12 597, 11 960, 11 778, 11 590 mg/kg and 11 290 mg/kg under the maize-wheat（2a） ＋ millet rotation, pea - wheat （2a） ＋ millet rotation, sainfoin - wheat （2a） rotation, pea - wheat （2a） ＋ maize rotation, wheat succession and wheat（2a） ＋ millet- maize rotation systems, respectively. The accumulation of exchangeable Ca in soil profiles （0 - 200 cm） under the maize - wheat（2a） ＋ millet rotation is 269.67 t/hm2, which is higher than those of other treatments. However the accumulation of exchangeable Ca in soil profiles （0 ~ 200 cm） under the wheat succession is 218.78 t/hm2, which is lower than those of other treatments. The results suggest that different crops and cropping sys- tems have effects on exchangeable Ca distribution in soil profile. The results also indicate that the total accumulation amount of exchangeable Ca in soil profiles （0 - 200 cm） are not significantly different in various cropping systems.