改性磷矿粉在石灰性土壤上的生物有效性及其机理研究

为缓解磷资源危机,充分利用不适于化学加工的磷矿资源,对磷矿采用活化技术开发利用,由此生产的改性磷肥已被证明在酸性土壤上有很高的生物有效性,但在石灰性土壤上的研究还比较少。本文选择4种不同产地(云南昆明、四川德阳、四川绵竹和贵州开阳)的磷矿粉,分别用有机活化剂和无机活化剂进行活化处理,制备改性磷矿粉,并就其在石灰性土壤对苗期春小麦的生物有效性进行了盆栽试验。结果表明,4种磷矿粉经活化处理后有效磷和水溶性磷含量均明显增加,无机活化剂提高了有效磷的含量,而有机活化剂对水溶性磷的提高幅度较大。改性磷矿粉处理均不同程度提高了石灰性土壤上春小麦的生物量干重、植株吸磷量和磷利用效率,有机活化剂处理制备的改性磷矿粉对春小麦生长的促进作用更为明显。运用红外光谱谱学技术对4种磷矿粉及相应的8种改性磷矿粉结构分析结果表明,磷矿粉经改性后其结构发生了明显变化,H2PO4和HPO42的特征谱带明显增加,增加的程度因磷矿粉的产地和活化剂种类不同而有差异。对磷矿粉化学成分分析结果表明,不同产地的磷矿粉其磷以及钙、铁、铝、镁等化学成分的含量差异较大,活化剂对磷矿粉的活化效果与磷矿粉本身的氧化物含量有关。在本试验条件下,磷矿粉Ⅲ(四川绵竹)的活化效果相对最好,与其氧化镁含量最高、总氧化物含量最低有关。不同类型活化剂对磷矿粉的活化效果不同,红外光谱分析结果表明,无机活化剂活化效果较好,而土培试验结果表明有机活化剂的活化效果较好,这一结果有待进一步的研究。

Bioavailability and mechanism of modified rock phosphate in calcareous soil

Phosphorus is among the most plant essential nutrient elements.High yields and good qualities of crops are efficiently promoted by the application of plenty soluble phosphorus fertilizers.Utilization efficiency of soluble phosphorus fertilizers,however,remains generally low because of its unique chemical properties.This has posed a significant challenge for natural resources of phosphorus and rock phosphate.Furthermore,the use of rock phosphate resources as high concentration phosphorus and compound fertilizers was limited in China.It was therefore important to develop the most efficient utilization technique for the sustainable usage of rock phosphate resource with meaningful economic benefits of phosphorus fertilizer incorporation.Rock phosphate activation to release efficient,non-acid-driven phosphorus and utilizable byproducts in industries and agriculture was one such technique.Although few current studies conducted in acid soils indicated high bioavailability of new phosphorus fertilizers derived from activated rock phosphorus(the so-called modified rock phosphate),less studied was conducted in calcareous soils.This paper explored the availability of modified rock phosphate in calcareous soils of North China and the possible mechanisms of activation effects.The findings of the study could enhance industrial production and application of modified rock phosphate in different soil conditions.In this paper,rock phosphates from different producing areas Kunming City of Yunnan Province(RPⅠ),Deyang City of Sichuan Province(RPⅡ),Mianzhu City of Sichuan Province(RPⅢ),Kaiyang City of Guizhou Province(RPⅣ)] were activated by both organic and inorganic activators to get modified rock phosphate.The P bioavailability of the modified rock phosphates in calcareous soils were also tested for spring wheat in pot experiments.Compared with the rock phosphates,the results showed improvements in available and soluble P in modified rock phosphates.Also while the use of inorganic activator improved available P,organic activator largely improved soluble P.Modified rock phosphate improved dry matter content,and P uptake and utilization efficiency of spring wheat in calcareous soils.Modifying rock phosphates with organic activator had more significant effect on spring wheat growth.Measured structures using the Infrared Spectrogram(IS) technique showed significant changes in rock phosphate structures after activation.Compared with normal rock phosphates,increased characteristic H2PO4 and HPO42 spectrograms were noted.The increasing effects varied among rock phosphates producing areas and activator types.This indicated that activation promoted release of available P in rock phosphates.Rock phosphates from different areas were different in chemical components such as phosphorus,calcium,iron,aluminum and magnesium.Chemical measurements showed that activation effects were related with rock phosphate oxide content.In the four rock phosphates,RPIII showed the best activation effect.MgO content of RPIII was the highest and total oxide content was the lowest.This was the possible reason behind the best effect produced by RPIII-i.e.,the higher MgO content induced a higher solubility of rock phosphates.Different activators exhibited different activation effects even for the same rock phosphate.Although IS structure measurement suggested that inorganic activator was better,soil plant experiments showed that organic activator was better.Due to these contrasting results,further studies were recommended in this direction.