Effects Of Microbial Inoculants On Soil Fertility As Well As Potato Yield And Quality

The fertilization status of potato production using only chemical fertilizers caused the yield of potato bottleneck problem and soil fertility declining in China. This experiment was conducted using potato and microbial fertilizer as research object to study the effect of different microbial fertilizers and different dosage on potato growth, yield, quality and soil biochemical properties, soil nutrient availability over the growing season under field conditions. For the experimental design, DMF(Double M Fertilizer) was set to 0 kg/hm2, 7.5kg/hm2, 15kg/hm2, 30kg/hm2 4 levels denoted as A0, A1, A2, A3 respectively; BPF(Biological Potassium Fertilizer) was set to 0 kg/hm2, 15 kg/hm2, 30 kg/hm2, 60 kg/hm2 4 level named as B0, B1, B2, B3, respectively on top of the traditional chemical fertilizer application rate. The results showed:DMF, BPF and two fertilizer’s combination increased soil biochemical activity, soil nutrient content. The effect of this fertilization used in the experiment was obviously superior to the traditional fertilization. In the whole growth period, DMF promoted soil ammonification intensity obviously with the maximum value under B2A2 treatment, increasing 36.52% compared with the control(B0A0 treatment). BPF improved soil ammonification intensity significantly at tuber enlargement stage and starch accumulation stage. However, the combination of DMF and BPF promoted ammonification intensity only at the tuber expansion stage. BPF increased soil organic phosphorus transformation strength significantly with the highest under A2B2 treatment in whole growth season, resulting in soluble phosphorus increment averaged by 17.15% compared to A0B0. DMF and the combination of two fertilizers had no obvious effect on soil inorganic phosphorus transformation.DMF and BPF promoted on soil potassium availability over the potato growing season. The effect of BPF(F=22.38) was significantly more than that of DMF(F=10.95). DMF, BPF and two fertilizer’s combination promoted soil alkaline hydrolysis N and available K content. The soil alkali hydrolyzable N content was 114.6~129.0mg/kg under B1A3 treatment, which was the highest, followed by B2A2, increasing of 12.6% and 11.6% respectively. The BPF increased soil available K content to 298.2mg/kg under B3 treatment, which was the highest value and by 5.31% higher than that of control. Soil available P content was not significantly different under each treatment.DMF, BPF and two fertilizer’s combination promoted potato plant height significantly, and the B2 was the highest treatment, under which plant height was 70.37 cm and increased 12.43% compared with B0A0. BPF did not obviously increase stem diameter, however DMF promoted stem diameter, which was the biggest under B2A2 treatment, increasing 1.92 mm compared with control. Each treatment increased potato yield by 8.25~23.10%. The B3A2 treatment was the highest value, followed by B2A2, which were 35375kg/hm2 and 35040kg/hm2 respectively. The maximum large and medium tuber rate was under B2A2 treatment. However, the level of A3 treatment decreased large and medium tuber rate significantly. DMF, BPF and two fertilizer’s combination promoted potato quality. The dry matter content, Vc content and protein content in potato tube were increased significantly, and the reducing sugar content was decreased obviously. The tuber starch content was not significantly changed over the experimental treatments.The application rate of DMF at 15kg/hm2 and BPF at 30kg/hm2 combined with chemical fertilizers was recommended as the optimal fertilization rate for potato production at this region after comprehensive consideration of potato yield, quality and soil fertility.