阴山南麓复种燕麦箭筈豌豆间作和施氮对土壤特性和饲草产量的影响

为探究内蒙古阴山南麓地区饲草间作和施氮对土壤特性和饲草产量的影响，以饲用燕麦和普通箭筈豌豆为材料，于2020—2021年开展田间小区试验，设置 3 种种植模式(OV:燕麦箭筈豌豆间作；MO:燕麦单作；MV:箭筈豌豆单作)和3 个施氮水平(N0:0 kg/hm²；N75:75 kg/hm²；N150:150 kg/hm²)。研究不同种植模式和不同施氮量下土壤氮素含量、土壤速效养分含量及饲草干草产量的变化规律。结果表明，随施氮量增加土壤全氮含量呈增加趋势，间作较单作提高了土壤全氮含量，所有处理以OV-N75土壤全氮含量最高，2年较N0分别提高50.89% 和4.76%；随施氮量增加土壤碱解氮含量呈增加趋势，在N150水平达最高，所有处理以OV-N150处理最高，2年较N0分别提高9.54% 和29.15%，但与N75水平无显著性差异(P>0.05)；间作结合施氮增加了土壤硝态氮含量，所有处理以OV-N150处理最高，2年较N0分别提高113.60% 和119.64%；土壤铵态氮含量以MV模式最高，且在N150施氮水平达最大值，2年较N0分别提高18.13% 和69.37%。不同施氮水平下3种种植模式土壤pH均表现为MO>MV>OV，所有处理以2020年OV-N75处理土壤pH最低，较其他处理降低0.38%～3.40%；施氮有利于增加土壤有机质含量，所有处理以MV-N150处理土壤有机质含量最高，2020年较N0和N75分别提高14.45% 和9.70%，2021年较N0和N75分别提高32.54% 和6.23%；随施氮量增加土壤有效磷含量呈增加趋势，3种种植模式均在N150处理达最高，但与N75水平无显著性差异(P>0.05)，其中OV模式N75处理2年较N0分别提高11.31% 和29.73%；施氮较不施氮显著增加土壤速效钾含量，但N75与N150水平无显著性差异(P>0.05)，其中OV模式N75处理2年较N0分别提高7.57% 和24.12%。施氮对土壤微生物量碳、氮含量的影响极显著(P<0.01)。间作结合施氮提高了土壤微生物量碳、氮含量，以OV模式土壤微生物量碳含量最高，2年N75处理较N0分别提高76.16% 和71.72%；以MV模式土壤微生物量氮含量最高，2年N75处理较N0分别提高217.56% 和184.28%。不同种植模式燕麦和箭筈豌豆随施氮量增加干草产量呈增加趋势，间作模式以N150处理干草产量最高，2年干草产量N75较N0分别提高了29.41% 和27.54%，N150较N0分别提高了36.60% 和51.21%。综上，燕麦箭筈豌豆间作模式能够提高该地区饲草种植多样性，提高土壤氮素含量和速效养分含量，且在75 kg/hm²施氮条件下与150 kg/hm²无差异性显著(P>0.05)，较不施氮相比显著提高饲草干草产量，更适于阴山南麓地区推广种植。

Effects of oat and common vetch intercropping and nitrogen application on soil properties and forage yield at the southern foot of Yinshan Mountain

In order to investigate the effects of forage intercropping and nitrogen application on soil characteristics and forage yield in the southern foothill of Yinshan，Inner Mongolia，a field plot trial was conducted in 2020 to 2021 based on the forage oat and common vetch，and three planting patterns（OV：intercropping of oat and common vetch；MO：monoculture oat； MV：monoculture common vetch）and three nitrogen application levels（N0：0 kg/hm² ；N75：75 kg/hm² ；N150：150 kg/ hm² ）were set up. The changes of soil nitrogen content，soil available nutrients content and forage hay yield under different planting patterns and different nitrogen application rates were studied. The results showed that the soil total nitrogen content showed an increasing trend with the increase of nitrogen application rate，and the soil total nitrogen content was increased by intercropping compared with single cropping. The soil total nitrogen content of OV-N75 was the highest among all treatments， which was increased by 50.89% and 4.76% compared with N0 in two years，respectively. Soil alkali-hydrolytic nitrogen content showed an increasing trend with the increase of nitrogen application rate，and reached the highest at N150 level，and OV-N150 treatment had the highest value，which was 9.54% and 29.15% higher than that of N0 in two years，respectively， but had no significant difference with N75 level（P＞0.05）. Intercropping combined with nitrogen application increased soil nitrate nitrogen content，and OV-N150 treatment was the highest，which was 113.60% and 119.64% higher than N0 in two years，respectively. The soil ammonium nitrogen content in MV mode was the highest，and the nitrogen level in N150 was the highest，which was 18.13% and 69.37% higher than that in N0 in two years，respectively. Under different nitrogen application levels，the soil pH of the three planting modes was MO＞MV＞OV，and the soil pH of OV-N75 treatment in 2020 was the lowest，which was 0.38%-3.40% lower than that of other treatments. Nitrogen application was beneficial to increase soil organic matter content，and MV-N150 treatment had the highest soil organic matter content，which was 14.45% and 9.70% higher than that of N0 and N75 in 2020，and 32.54% and 6.23% higher than that of N0 and N75 in 2021. The soil available phosphorus content showed an increasing trend with the increase of nitrogen application rate，and reached the highest value in N150 treatment，but had no significant difference with N75（P>0.05）. The content of OV-N75 treatment increased by 11.31% and 29.73%，respectively，compared with N0. Nitrogen application significantly increased soil available potassium content compared with no nitrogen application，but there was no significant difference in N75 and N150 levels（P>0.05），and OV-N75 treatment was 7.57% and 24.12% higher than OV-N0 treatment in two years，respectively. The effects of nitrogen application level on soil microbial biomass carbon and nitrogen contents were significant（P<0.01）. Intercropping combined with nitrogen application increased soil microbial biomass carbon and nitrogen content，and the OV model had the highest microbial biomass carbon content，which was 76.16% and 71.72% higher than that of N0 in two years under N75 treatment，respectively. MV mode showed the highest soil microbial biomass nitrogen content，and N75 treatment increased by 217.56% and 184.28% compared with N0 in two years，respectively. The hay yield of oat and common vetch under different cropping modes showed an increasing trend with the increase of nitrogen application rate. The hay yield of N150 treatment was the highest，and the 2-year hay yield of N75 was increased by 29.41% and 27.54%，and that of N150 was increased by 36.60% and 51.21% compared with N0，respectively. In conclusion，the intercropping oat and common vetch model could improve the forage diversity，soil nitrogen content and available nutrient content in this region，and there was no significant difference between the intercropping oat and common vetch under 75 and 150 kg/hm² nitrogen application condition（P>0.05），which was more suitable for promoting planting in the southern foothill of Yinshan Mountain.