| Agriculture organic waste is greatly produced, has complicated composition and is responsible to the serious pollution to the surrounding environment in recent years. On the other hand, it contains large quantities of nutrients and organic matter and thus can be applied to meet the needs of crop for nutrients, and to improve the soil physical and chemical properties. So, it is often used as raw material for composting. But under the influences of the variety of raw material and the complex nutrient characteristics of raw materials, etc., the enterprises is lack of scientific guidance of the selection of compost raw materials. In this study, the research object is the agricultural organic waste for composting fermentation. Based on a wide range of data collection and social research, firstly, the sources of raw material, it's nutrient characteristics, principles for composting formula were reviewed and discussed; Secondly, the current situation of the selection of raw materials and compost formula were investigated. We also studied on the cost and quality of compost product with different formulas. According to the nutrient characteristics and prices of different raw materials, we propose the concept "nutrient use-cost" to guide the selection of raw material and the formula design.Based on the above analysis, the main conclusions are listed as follows:(1) At present, the sort of raw materials used for compost is rich, which including livestock and poultry manures (chicken, pig or rabbit manure), crop residues (chaff of rice, castor skin and tobacco peduncle powder, etc), agricultural and sideline products scraps (monosodium glutamate slag, tea-leaf and mushroom residue, etc) and other organic wastes (plant ash, danty and peat soil, etc.). The enterprises we investigated in this research have 21 kinds of raw materials for compost. Each has 5-14 kinds of raw materials for the selection of compost formula.(2) The proportion of raw materials with organic matter>50% is 38.1%. These materials are the debris of plants, offcut of agricultural product and livestock and poultry manures including tea-leaf, rapeseed dregs, castor meal, castor skin, tobacco peduncle power, chaff of rice, pig manure and dung of silkworms with 67.86%,60.00%,55.74%, 54.79%,54.75%,53.50%,51.90 and 50.63% of organic matter contents, respectively. The materials are usually used to adjust C/N and water content in the compost formula.(3) The contents of N in castor meal (5.09%), rapeseed dregs (6.00%) and yeast slug (5.70%) are higher than other materials. The second is tea-leaf, castor skin, MSG slug, molasses dregs and dung of silkworms with 2.90%,2.69%,3.54%,2.36% and 2.17% of N content, respectively. The N contents of peat soil, danty and plant ash are the lowest in the 21 raw materials. The P content of 90% of materials is less than 2.0%. Impressively, the P content of bone meal is up to 26.50%. As for K content of the materials, most are ranging from 0.2 to 2.5%, except for danty and bone meal, the K contents of which are below the limit of detection. Part of the raw materials contain high K, such as plant ash, tobacco peduncle power, mushroom residue and sea-tent power with 5.82%,5.41%,4.43% and 12.20% of K contents. The materials with high N, P and K contents are often used to adjust C/N and to enhance nutrient contents.(4) The most important principle of composting is to reduce cost and also to ensure product quality. In this paper, we proposed a concept "nutrient use-cost" to guide the selection of raw materials for composting. The N use-cost of mushroom residue, tea-leaf, dregs of molasses and yeast are less than 15.0￥/kg. The P use-costs of bone meal and plant ash is 5.6 and 7.3￥/kg, respectively. The K use-costs of plant ash and sea-tent power is 2.1 and 1.9￥/kg, respectively. Based on the data, these raw materials could be used for composting to adjust N, P and K contents.(5) According to the analysis of total primary nutrients use-cost, we can clearly understand the selection of raw material for composting. The total primary nutrients use-cost of the twenty-one raw materials we investigated ranges from 1.5-55￥/kg.61.9 percent of raw materials, such as chicken manure, tobacco peduncle power, pig dung and tea-leaf, et al., are often used for composting, since the total primary nutrients use-cost is less than 10￥/kg. The use-costs of total primary nutrients of castor bean meal, rapeseed dregs were high, so only a few enterprises chose them for composting. The price of chaff was lower than other raw materials. The enterprises often use it to adjust water content, but not to enhance nutrient content, because the total primary nutrients use-cost is high than most of the other raw materials.(6) The organic matter contents in the compost formulas of the 8 enterprises ranges from 40 to 50%, and the contents of the total primary nutrients (N, P and K) ranges from 3-7%. The contents of the total primary nutrients in compost formula of enterprise 2 reached up to 6.71%, as a result, the cost of compost formula is high to 500￥/ton. The total primary nutrients contents of 62.5% companies ranges from 3-4%, and the costs of compost formulas ranges from 300-400￥/ton. The nutrient use-cost of organic matter, N, P and K in the compost formula ranges from 0.4-1.3,18-32,25-45,14-28￥/kg, respectively. The total primary nutrients use-cost ranges from 5-12￥/kg. The organic matter and total primary nutrients use-costs of enterprise 6 were the lowest in the 8 enterprise. The organic matter and total primary nutrients contents were high than or equal to most of the enterprises, and the cost of compost formula was lowest. All the results showed that the compost formula of enterprise 6 was the best.(7) From the view of product quality of compost, it is better to choose the dregs of rice such as castor bean meal, rapeseed dregs as raw materials. The proportion of these raw materials should be 20-30% in the compost formula. However, as the high price of the materials, people use Edihle fungi residue to partly replace castor bean meal or rapeseed dregs to reduce cost. In this way, the product quality can also be guaranteed. Compared with other raw materials such as Edihle fungi residue, tea-leaf and mushroom residue, the content of organic matter of danty is higher. So, it is better to choose danty to enhance the content of organic matter of the product. The power of tobacco peduncle contains more K, and also contains nicotine which can drive the pest away, so it is always used as the major ingredient of compost formula. Plant ash also can be used to enhance K content.In a word, based on the analysis of nutrient use-cost, the compost enterprise can make a scientific compost formula to reduce cost and to ensure product quality. |
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