| With the increase of people population, agriculture and chemical fertilizer usage etc., soil quality, crop yield and quality declined severely. At the same time, with the development in industry, agriculture and people population, the atmosphere CO2 concentration is keeping raising, ecological disasters which come from "the greenhouse effect" are constantly appearing. Therefore, how to improve the soil and promote the accumulation of C sinks in soil are problems urgent to be solved. In view of the facts that organic matter and microorganisms can play great roles in soil inprovement, chemical fertilizer (CF) usage can acidify the soil, microorganisms and the acidified environment can promote mineral weathering, and along with the mineral weathering, the available mineral elements and C elements in soil increased. In this paper, the bio-organic-mineral fertilizer (BMF), which was composted by organic matter, K-feldspar powder and microbes, was introduced to the barren soil and CF-oversuppliedsoil to analyze the roles of the BMF on the soil improvement, soil C sink accumulation as well as promotion in plant growth and quality. The main results were as follows:After the BMF was applied into the barren soils for 60 days with OF, CF and MF as the controls, results showed that the control soil was slightly alkaline; treatments of BMF and OF reduced the soil pH slightly, while the CF treatment reduced the pH significantly. As for the EC values, it came the highest in the BF treatment, and came the lowest in the CF treatment after 60d treatment. Fertilizers of the BMF, OF and MF improved the activities of urease and alkaline phosphatasein soil, while, the CF appliance inhibited the above 2 soil enzyme activities. And the improvement effects of the BMF on the 3 soil enzyme activities (urease, alkaline phosphatase and CA) and contents of AK (available potassium), AOC (active organic carbon) and HCO3- etc. were the most significant.As to the soil properties, the growth-promoting effect of the CF treatment was the most obvious after a short-term treatment; and as time went on, the effects of the OF treatment gradually exceed the CF group. Although the water spinach growth-promoting effect of the BMF treatment is weaker than the treatments of OF and CF, its effects on the improvement in soil quality and water spinach quality which including increase in flavonoids and other beneficial nutrients contents and decrease in nitrate and oxalic acid contents. In addition, BMF treatment also enhanced the CA activity in water spinach. And as time went on, the improvement effects of the BMF treatment became more and more significant.To exclude the interference of plants and leaching, the barren soils were just applied with fertilizers without plants and watering for 60 days treatment. Results showed that treatments of BMF and MF slightly increased the soil pH and treatments of OF and CF acidified the soil, and the strongest acidification role was found in the CF treatment. Without plant uptake and leaching, each fertilizer treatment increased the soil EC significantly. Plant uptake and leaching greatly reduced the soil EC, and the largest reduction was found in the CF treatment. Treatments of BMF and OF accelerated the mineral elements cycling and AOC and HCO3- accumulation in soil. Although the CF treatment could increase the available mineral nutrition contents quickly, it decreased soil enzymes’ activity, inhibited mineral elements cycling and reduced the C accumulation in soil. Water spinach cultivation and leaching were unfavorable for elements cycling, soil enzyme activity improvement and C accumulation in soil.To explore the roles of the BMF on the CF-oversupplied soil and on the recover and quality improvement of purslane, the BMF was introduced to the CF-oversupplied soil. Results showed that excessive CF reduced the soil quality, which including soil acidifying, N elements loss, soil enzyme activities and HCO3-content decrease etc. The BMF treatment stabilized soil pH, increased the contents of TK (total K) and AK (available K), enhanced soil enzyme activities and promoted soil supply capacities on N and P, and promoted carbon accumulaton in soil and in purslane When excessive CF was applied with gradient BMF, the soil acidification and soil enzyme activities’ inhibition were eased, and soil’s suppling capacity of N and K was higher than that in the only BMF treatment. And combined treatments of BMF and excessive CF promoted C releasing when C/N ratio was below 10 and accelerated carbon accumulation when C/N ratio was over 10. Purslane could not grow in the CF-oversupplied treatment, only BMF treatment promoted purslane grow, and when excessive CF was applied with gradient BMF, purslane growed gradually restored and the nutrient contents were raised higher in the combined treatments than in the separate CK or BMF treatment. |
