我国紫花苜蓿主产田土壤养分和植物养分调查分析

科学合理施肥是保证植物正常生长,提高肥料利用率,解决生产和环境问题矛盾的重要途径.为了掌握我国紫花苜蓿在生产中的施肥管理状况,在2012年和2013年两年对我国北方紫花苜蓿主产区49个样地土壤养分和植物养分以及苜蓿第一茬产量进行调查分析,并针对紫花苜蓿的施肥管理向种植户(包括企业)开展了问卷调查.结果表明, 1)我国紫花苜蓿主要集中种植在相对贫瘠的砂性土壤上.在调查的49个样地中,砂性土壤占总样点数的71.4%,主要在内蒙古,甘肃和新疆.大部分样地的土壤有效氮丰富,仅10%的样地因为沙质土壤中有机质含量极少而导致土壤有效氮缺乏.有24.5%的样地土壤速效磷缺乏,其中10.2%的样地速效磷处于极缺水平;有10.2%的样地土壤速效钾缺乏(样地数N=49).土壤中量元素Ca和Mg较为充足.微量元素中有32.2%的样点有效铁缺乏(N=28),主要分布在甘肃和内蒙古;7.1%(N=28)的样点有效锰缺乏,分布在甘肃和内蒙古.有14.3%的样点有效铜缺乏(N=28),其中有一个分布在甘肃,其余3个样点在内蒙古;有50%的样点有效锌缺乏(N=28),其中8个处于极缺状态(甘肃,陕西各3个,内蒙古2个),6个处于缺乏状态(山东3个,河北,陕西和黑龙江各1个);有10.7%的样点有效钼含量缺乏(N=28),主要分布在内蒙古.有效硼含量处于丰富状态(N=28).2)苜蓿植株氮素营养状况较好,而磷钾营养状况较差.微量元素中钼有49%的样点出现缺乏(N=49).相关性分析结果表明土壤全磷和速效磷都与产量具有显著的正相关关系(P<0.05),说明施用磷肥对苜蓿具有显著的增产潜力.3)在调查的49个样点中有18个样点没有进行任何施肥措施,其中大多数为农户.施氮肥作为提高产量的手段占57.1%,大多数为企业种植者.磷肥重视程度高于钾肥,有41%的样地施用磷肥,仅有26.5%的样地施用钾肥.对有机肥重视不够(仅有8个样地施用有机肥).所有种植者均没有施用过微肥.总之,我国紫花苜蓿主产区在生产实践中应少施或不施氮肥,应重视磷钾肥的配施,也应重视微量元素的作用,尤其是钼元素.

Analysis of soil and plant nutrients in alfalfa fields in China

A scientific approach to fertilizer management is important to ensure optimal plant growth,high fer-tilizer use efficiency and to resolve the contradictions surrounding production and environmental issues.In or-der to understand fertilizer management in alfalfa production,a survey was conducted to investigate alfalfa yield at first cut,as well as soil nutrients and plant nutrient content in 49 alfalfa fields in northern China over two years (2012 and 2013 ).Simultaneously,a survey (questionnaire)was conducted to determine how alfalfa growers (including farmers and corporate growers)managed fertilizer application.Alfalfa was mostly planted in relatively barren sandy soils.Among 49 fields,35 fields were sandy soil (71.4%),mainly in Inner Mongo-lia,Gansu and Xinjiang.Soil available nitrogen (N)was high in most fields and deficient in only 10% of fields, mainly due to extremely low organic matter content.Available phosphorus (P)was low in 24.5% of fields and very low in 10.2% of fields.Available potassium (K)was low in 10.2% of fields.Calcium and magnesium were plentiful in all soils.Analysis of micronutrients revealed that 32.2% fields had low available iron (mainly Gansu and Inner Mongolia);7.1% of fields low available manganese (Gansu and Inner Mongolia);14.3% of fields had low available copper (1 field Gansu,3 Inner Mongolia);50% of fields had low available zinc;10.7%of fields had low available molybdenum (Mo)(mainly Inner Mongolia);conversely all fields were high in avail-able boron.The alfalfa stands generally had good N nutrition but were low P and K.Among 49 fields 49% of fields had low Mo.Correlation analysis showed that soil total and available P were significantly positively cor-related (P <0.05)with alfalfa dry matter yield,suggesting that P fertilizer would significantly increase alfalfa yield.Growers of 18 fields,mostly farmers,didn’t apply any fertilizer.57.1% of growers applied N to in-crease yields,mostly corporate growers.Phosphate was applied to 41% of fields K to 26.5%.Organic fertiliz-er was only applied in 8 fields.Micronutrients were not applied to any crops.It was concluded that application of N to alfalfa was relatively common,contradicting the ability of the crop to biologically fix N.Soil P and K levels in soils were low,especially K in China,suggesting that many alfalfa crops would benefit from applica-tion of these nutrients.Molybdenum may be limiting in some alfalfa crops.