| At present excessive accumulation of phosphorus in farmland soils had led to a decrease in phosphorus utilization rate and soil quality,affected crop growth,increased soil phosphorus environmental risks,and restricted the sustainable development of farmland.In order to alleviate the accumulation of soil phosphorus,this paper conducted a four-stubble pot and three-stubble field experiment to study the effects of different conditioners on the transformation of phosphorus forms in high-phosphorus soils and their crop uptake.The pot experiment used waxy corn as the test crop,and humic acid,woody peat,bentonite,zeolite,alum,dephosphorized gypsum,dolomite,silicon calcium material and biochar were used as test materials.According to the characteristics and mechanism of the conditioners,Three treatments of nutritional conditioners(NC),five treatments of passivation conditioners(PC),nine treatments of coordination conditioners(CC)and one blank treatment(CK)were designed.In the field experiment,summer corn and winter wheat were used as test crops,and humic acid,biochar,alum,and silicon calcium were used as test conditioners.Seven treatments were designed,which were T1 blank treatment,T2 humic acid,T3 biochar,T4 Alum,T5 silicon calcium material,T6 biochar + alum and T7 humic acid + biochar + alum.The effects of different conditioning agents on the transformation,absorption and crop growth of soil phosphorus were studied through changes in crop growth,dry biomass,phosphorus absorption and soil available phosphorus,water-soluble phosphorus,total phosphorus,inorganic phosphorus and organic phosphorus content.The specific research results were as follows:The results of four-crop pot experiment showed that,according to the growth of waxy corn,dry matter weight and phosphorus absorption,Biochar + bentonite + alum treatment was beneficial to increase the plant height,leaf photosynthetic rate,dry matter weight and phosphorus absorption of waxy corn.Biochar,humic acid + silicon calcium material + biochar treatment had a better effect on improving leaf photosynthetic rate and chlorophyll content,and biochar treatment was also beneficial to increase phosphorus absorption.Humic acid + bentonite + biochar + alum + dephosphorized gypsum treatment had a better effect on increasing the stalk thickness,dry matter weight and phosphorus absorption of waxy corn.Dolomite treatment increased the plant height of waxy corn in the second and third crops by 20.5% and 39.1% compared with CK treatment,at the same time,it was beneficial to increase the stem thickness,leaf photosynthetic rate,dry matter weight and phosphorus absorption of waxy corn.In terms of soil,woody peat treatment had a better effect on reducing soil water-soluble phosphorus and available phosphorus content.Woody peat + dolomite + dephosphorized gypsum + bentonite treatment significantly reduced the soil water-soluble phosphorus content in the third crop by 37.8% compared with CK treatment.Humic acid + bentonite + biochar + alum + dephosphorized gypsum treatment could reduce the content of available phosphorus and water-soluble phosphorus in the soil,and the content of soil available phosphorus in the second and third crops was significantly reduced by 12.0% and 18.4% compared with CK treatment.Dolomite,humic acid + silicocalcium material + biochar,woody peat + dolomite + dephosphorized gypsum + bentonite treatments had better effects on reducing soil total phosphorus content.Combining crop growth,phosphorus absorption,and soil phosphorus absorption and transformation,dolomite,humic acid + silicocalcium material + biochar,humic acid + bentonite + biochar + alum + dephosphorizing gypsum treatments was better.Comprehensive field experiment results of summer corn-winter wheat-summer corn three stubble field results showed that biochar + alum and humic acid + biochar + alum treatments had a better effect on crop growth.In the second crop,The yield and biomass of other parts of winter wheat with silicon calcium materials treatment were the highest,being 12.23 and 18.97 t/hm2.In the third crop,the biomass of other parts of summer maize with biochar treatment was highest at 10.96 t/hm2,and the grain phosphorus absorption amount with silicon-calcium material treatment was the highest at 46.68 kg/hm2.Biochar and silicon-calcium material treatments had significant effects on increasing crop biomass and promoting phosphorus absorption of maize and wheat.In terms of soil phosphorus absorption and transformation,humic acid,biochar,alum,humic acid + biochar + alum treatments had a better effect on reducing soil effective phosphorus content than other treatments.Alum and silicon-calcium materials treatments was effective in reducing the content of water-soluble phosphorus in the soil.The effect of humic acid treatment on reducing soil total phosphorus content was better,which was 1.1%-9.4% lower than that of T1 treatment.Biochar + alum treatment was beneficial to increase the proportion of soil inorganic phosphorus in the total soil phosphorus content,and the content of inorganic phosphorus components Ca2-P,Ca8-P,Al-P,Fe-P,O-P was significantly higher than the blank treatment in the third crop.The effect of humic acid + biochar + alum treatment on soil phosphatase activity was better.Combining crop growth,phosphorus absorption,and soil phosphorus absorption and transformation,biochar + alum and humic acid + biochar + alum had better effects. |
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