不同覆盖方式对旱地胡麻土壤硝态氮和籽粒产量的影响

Effects of different mulching modes on soil nitrate concentration and grain yield of Linum usitatissimum in dry land

为了探讨黄土高原旱作雨养条件下覆盖种植胡麻田土壤硝态氮动态特征和增产效果,在2015和2016年胡麻生长季,以常规种植模式为对照(CK),研究了3种覆盖方式(全膜微垄覆土穴播、全膜覆土穴播和秸秆覆盖条播)对胡麻籽粒产量和关键生育时期农田硝态氮分布的影响.结果表明:与CK相比,覆盖处理的胡麻籽粒产量分别增加56.1%(2015)和22.7%(2016),且均以全膜覆土穴播处理的籽粒产量最高.覆膜提高了胡麻根际土壤水分含量,在整个生育期的影响程度为先增加后降低;随着胡麻生育进程的推进,土壤硝态氮含量逐渐降低.两年试验中,覆盖处理下胡麻现蕾期0~40 cm土层硝态氮含量分别比CK增加3.1%~18.6%(2015)和5.1%~16.4%(2016),其中,全膜覆土穴播的增幅最大.2015年,胡麻盛花期和成熟期0~100 cm土层土壤硝态氮积累量较CK分别增加10.2%~22.2%和8.6%~21.4%,特别是在降雨较多的成熟期,0~40 cm土层土壤硝态氮含量较40~100 cm土层显著提高3.3%~4.9%,说明覆盖处理可以减缓硝态氮向下层的迁移.2016年,生育后期的高温干旱对胡麻生长造成了极大的影响,胡麻成熟期覆盖处理0~100 cm土层硝态氮积累量较CK显著增加6.6%~18.0%.相关分析表明,胡麻关键生育时期不同土层的土壤硝态氮含量与籽粒产量之间有显著正相关关系.综合考虑,全膜覆土穴播模式是适宜干旱、半干旱区推广应用的胡麻高产高效栽培方式.

To investigate soil NO3^--N dynamics and yield increasing effect of mulching planting for Linum usitatissimum（ oil flax） in semi-arid Loess Plateau,we examined the effects of three mulching modes（ whole field plastic mulching and micro ridges with soil cover and bunch-seeding;whole field plastic mulching with soil cover and bunch-seeding; and straw mulching with strips） on seed yield and distribution of soil NO3^--N during the main growth periods of oil flax,with the conventional planting model as control（ CK） in 2015 and 2016. Results showed that the average yield under mulching modes was increased by 56. 1%（ 2015） and 22. 7%（ 2016）. The treatment of whole field plastic mulching with soil cover and bunch-seeding had the highest grain yield. Mulching treatments significantly increased soil water content. Soil water content was increased first and then reduced in the whole growth stage of oil flax. The soil NO_3---N content was gradually decreased during the oil flax growth process. In both years,NO_3---N content in 0-40 cm soil depth under mulching treatments were increased by 3.1%-18.6%（ 2015） and 5.1%-16.4%（ 2016） at budding stage of oil flax,respectively. The whole field plastic mulching with soil cover and bunch-seeding treatment showed the larges increases across all treatments. In 2015,NO_3---N accumulation in 0-100 cm soil depth between the flowering and maturity stages of oil flax were increased by 10.2%-22.2% and 8.6%-21.4%,respectively. Especially during the more rainfall period of maturity stage,NO_3---N accumulation in 0-40 cm soil depth was significantly enhanced by 3.3%-4.9% than that in 40-100 cm soil depth. It indicated that more rainfall could slow down the migration of NO_3---N to the lower layer under the mulching modes in the maturity stage. In 2016,high temperature and drought at late growth stages had a great influence on oil flax growth. The NO_3---N accumulation in0-100 cm soil depth at the maturity stage was increased by 6. 6%-18. 0%. There was significant correlation between NO_3---N content and grain yield during the main growth stages of oil flax. In conclusion,the whole field plastic mulching with soil cover and bunch-seeding treatment was the most appropriate way of oil flax production in arid and semi-arid area.