雞糞生物炭添加對土壤中磷和銅鋅有效性與水稻生長的影響

Abstract

The poultry industry generates many kinds of litters which can cause environmental problems. Direct land application of poultry litter made a risk of excessive phosphorus (P) releasing into surrounding water. On the other hand, rice straws are major agricultural wastes after harvested, the residual straws are often left in the field and burned. A potential approach to utilize this poultry litter and rice straw is to transform it into poultry litter biochar (PLB) and rice straw biochar (RS) through pyrolysis, which may provide an environmental and economic benefits. Application of RS biochar to soil can increase nutrients, which can efficiently reduce the need for basalt fertilizer. Some mineral elements especially P of poultry litter are significantly concentrated in the PLB and turn into potentially available slow release nutrient source for crops. However, the containing of heavy metal ions of PLB would also be concentrated through high temperature pyrolysisprocess. Moreover, the effects of PLB amendment on the soil as the fertilizer to the rice still remain unclear. Therefore, the purposes of this study in this research are (i) to investigate the effects of different additional dosage and the different pyrolysis temeperature on the growth of rice plants and (ii) to study the maximum PLBs dosage which would have no negative effect on the growth of rice plants and accumulation of heavy metals. Poultry litter and PLB obtained under different pyrolysis temperature (350oC and 550oC) and RS biochar obtained with traditional burning method were conducted physical and chemical analysis. Biochar were applied as nitrogen (N) and P fertilizer and as soil amendement (0.5, 1.0, 2.5, 5.0%). The experiment results show that higher pyrolysis temperature could increase total carbon but decrease hydrogen and oxygen. Decreasing index of H/C and (O+N)/C means that changes the structure of PLB. FTIR results showed increasing pyrolysis temperature will increase aromatic C signals. The dominance P speciation in PLBispyrophosphate in 31P-NMR spectrum. The experimental results suggested that the pH of biocahrrange from 8.29 – 10.89. The total P concentrations of in PLBs were increased by increasing pyrolysis temperature, although this concentration remain low in RS biochar. Compared to the control, the data of crop height, numbers of tillering, and dry weight of root, shoot, and rice were significantly increased by the biochar treatment and the optimaltreatment obtain at 350oC with dosage 2.5% but plant dead with 5% biochar application. The effects of PLB application as N and P fertilizer and RS biochar showed had no effects with plant growth, biomass productivity and plant P concentration compared to control and chemical fertilizer (CF) treatment. Biochar treatment cause a miner increases of the P, Cu, and Zn concentrations in plants. P availability in soil increased with increasing biochar dosage compared to control. Biochar obtained at 550oC have lower P availability compared to biochar obtained at 350oC. It explainthe reasonthat biochar treatment at 550oC had lower plant growth and biomass productivity than biochar obtain at 350oC. P, Cu, and Zn release to soil solution is very low and generally decreased during plant growth. The availability of Cu and Zn in soil increased with increasing dosages of biochar but the concentration is under safe conditions. It was concluded that PLB produced 350ºC are better to improve paddy rice growth and productivity.