Effects Of Humic Acid Fertilizer On Growth Characteristic And Nutrient Quality Of Alfalfa

Medicago sativa plays an extremely important role in the sustainable development of grass industry and animal husbandry and dairy industry as an irreplaceable green forage grass with high-quality.With the development of stock farming, planting area of alfalfa is being expanded year by year, there have been large area of alfalfa planted in some sandy-soil regions, however, because of poor soil, the forage yield of alfalfa is low, and nutritional quality also declines. Such a situation, the scientific fertilization could improve production and quality of alfalfa planted in the sandy soil as a important measure. Humic acid fertilizer, as a new kind of organic fertilizer with the fuctions of conserving manure 、 high efficiency 、 enrichssoil nutrients、environmental protection, which is more applied on crops, but less applied on forage grass. Therefore, this study took with Medicago sativa L. cv. Gannong No.3 as material, and adopted the pot experiment, to discuss the effects of humic acid fertilizer on growth、yield and nutritional quality of alfalfa, with the aim of exploring its application effect and the best fertilization treatment. The results showed that:(1) The separate fertilization of Na HA or the combined application of Na HA-P had different degree of the promotion on growth and production indexes of alfalfa, while the combined application of Na HA-P could significantly promote them comparing with the separate fertilization of Na HA. With a certain level of P, the fertilizer combinations of Na HA and P had a performance that the growth rate, plant height, internode number, internode length and forage yield of alfalfa increased at first and then decreased as the increasing of Na HA dosage, stem-leaf ratio than vice versa; when P rose from P1 to P2, the combined application of Na HA-P1 significantly promoted the production indexes of alfalfa in comparison with Na HA-P2 combination. The results of Grey Relational Analysis on all tested production traits of different nitrogen treatments indicated that Na HA5-P1 combination, with the highest productivity of alfalfa(hay yield was 11.48 t/hm2), had the best performance of production traits.(2) The separate fertilization of Na HA or the combined application of Na HA-P had a certain improvement on nutrient quality of alfalfa, and the combined application of Na HA-P could significantly improve them. At the same time, the Na HA-P1 combination’s improvement on crude protein、crude fat、relative feeding value、neutral detergent fiber、acid detergent fiber and crude ash of alfalfa was better than Na HA-P2 combination. Taking the relative feeding value into consideration, Na HA5-P1 achieved the highest feeding value of alfalfa. According to the results of Grey Relational Analysis on all tested quality traits of the selected treatments, Na HA5-P1 combination had the best performance, the performance of CK was worst.(3) The separate fertilizer application of Sodium humate(Na HA) and the combined application of Na HA-P had a significant promotion on root length、root surface area、root average diameter、root volume、root forks、root crossings 、root activity、underground biomass and aboveground biomass of alfalfa comparing with the control CK, and the degree of the promotion presented that Na HA-P1 > Na HA-P2 > Na HA. Under the treatment combination of Na HA-P1, root morphological indexes、root activity and plant biomass of alfalfa increased as the increasing of Na HA dosage, however, which showed a trend of decline when Na HA rose from Na HA1 to Na HA5 or Na HA6. According to the biomass, Na HA4-P1 obtained the highest underground biomass, which was 1.288 g.(4) Taking production traits、quality traits and root traits into comprehensive evaluation, the comprehensive character of Na HA5-P1 was best, which indicated Na HA5-P1 had a greatest promotion on growth and development、hay yield and nutrient quality of alfalfa. Therefore, Na HA5-P1 was the best fertilizer combination among all selected treatments of this test, namely the humic acid sodium is 2118 kg/hm2, phosphate fertilizer is 642 kg/hm2.