Effect Of Ammonium Polyphosphate On Growth Of Maize Seedling

Ammonium polyphosphate（APP）is one of the important new kind of phosphate fertilizers which was introduced to China in recent years.The effect of APP on different soils,application methods,and long availability of phosphorus were not studied extensively.In order to investigate the effect of ammonium polyphosphates with various degree of polymerization on latosol,experiments were arranged using mono-ammonium phosphate（MAP）as the control and maize as the test crop.1)To simulate the field conditions with background levels of phosphorus（P₂O₅ by basal application were 0,0.05 g,0.10 g,0.20 g,0.30 g and 0.40 g/kg soil,respectively）,the effect of MAP and different APPs were studied on maize seedling,5 fertilizer formula treatments included no fertilizer（CK）,APP1,APP2and MAP were arranged.2)The effect of different phosphate fertilizers by one basal application on the growth of the seedling with two-season maize was researched,including5 treatments of CK（no fertilizer）,APP3,APP4,APP5 and MAP.3)The effect of different phosphate fertilizers by top dressing application including 8 treatments of CK（no fertilizer）,APP3,APP4,APP5,APP3:MAP（3:1）,APP4:MAP（1:1）,APP5:MAP（3:1）and MAP was arranged.The results showed as follows:（1）The dry weight and the P accumulation of corn increased with the increase of the phosphorus content applied.Different phosphorus sources affect corn fertilizer efficiency.When a small amount of phosphorus was applied,the soil available P was extremely low,shoot dry weight and phosphorus accumulation rate were affected by the P sources.The values of MAP were significantly higher than those of APPs,for APP hydrolysis was too slow to supply phosphorus nutrients at the early stages;When large P amount was applied,but with low soil available P,phosphorus sources showed no significant effect on shoot dry weight due to the fact that soil P could partially meet the requirement in the initial growth stage.However,the MAP treatment of the shoot phosphorus accumulation is still the highest under large P.Regardless of the P amount applied to soil,the effect of P sources was not significantly on the dry weight,nevertheless,had a certain effect on phosphorus accumulation rate of root and soil available phosphorus but there was no regularity.（2）Under basal application,effect of MAP was significantly better than that of APPs,for the first-season maize,which was showed in the plant height,dry weight,amount of phosphorus accumulation,and Soil available phosphorus.However,there was no significant difference among different APPs.For the second-season crop,the growth process of maize had shown the deficiency of phosphorus,and the treatment of phosphorus source had no significant effect on the growth of maize.（3）Under top dressing,the oligomeric APP combined with MAP（3:1）could promote maize seedling growth and nutrient uptake.Different APPs and MAP had significantly different effects on maize growth.For the first-season maize,results of APP:MAP and MAP were similar about biomass,and phosphorus accumulation,and both of them were significantly more than that of APP applied separately.The soil phosphorus declined sharply as the soil depth went deeper and deeper.Most of P was concentrated in the 0-2.5cm soil layer.Soil available phosphorus of MAP was the maximum.In the second season,the efficiency of maize（biomass and phosphorus accumulation）was significantly better than that of MAP,and there was no significant difference in soil effective phosphorus.（4）Under basal dressing,compared with the first season results,the values of biomass and P accumulation rate for the second season were significantly decreased.But under top dressing,P accumulation and dry weight of most APPs was increased significantly or better than APP obviously which indicated that APP showed the slowly releasing of P for the crop.