Characteristics Of Non-point Source Pollution Load Of Crop Farming In The Three Gorges Reservoir Area

Basing on objective data collected from interviews in typical villages of the Three Gorges Reservoir area by the methods of PRA(Participatory Rural Appraisal),and using ARCGIS and stepwise regression method et al., we divide the agricultural production and operation modes into General Farmers(GF), Big Farming Household(BF),Company Enterprise(CE), Big Breeding Household(BB), Big Farming and Breeding Household(FB), cooperation(CP) by organizing research materials and assessing research results integrated. Basing on the maximum objective decision function, the present study devised three livelihood scenarios related to rural transformation development: agriculturally dominant livelihood, multiple-type livelihood and non-agriculturally dominant livelihood. By accounting Different operating modes’ fertilizer input in per unit area, we have identified the characteristics of the structure and quantity of fertilizer among different agricultural operating patterns. On the basis of statistic data of land use and farmer interview, this paper analyzes the spatial distribution characteristics of pollution load of crop farming. Moreover, the present study reports the trend characteristics of non-point source pollution load of crop farming in relation to the transformation of dominant livelihood types. Three main results and conclusions are following.Part one: Crop farming structure and characteristics of fertilizers inputs among different agricultural operating patterns.(1)The total amount of fertilizer using shows an increasing trend and high concentrations of fertilizers( e.g. ceramide) and emerging fertilizer(e.g. Compound fertilizer) increase significantly in recent years;(2)Different business models have different structure of fertilizer using accordingly, here are internal similarities between General Farmers, Big Breeding Household and Big Farming with Breeding Household, the same to the Big Farming Household, Company Enterprise and cooperation. The former has a large proportion of using conventional fertilizer while the latter outstands more in the amount and the ratio of emerging fertilizer( organic fertilizer, K fertilizers, etc.);(3)The fertilizer structure of the study area is still dominated by conventional fertilizers, the input on N, P pure volume with various operating modes of per unit area is that the small-scale business operators use more than the scale business operators;(4)The planting structure is depended on agricultural operating patterns and the professional business patterns(such as Planting large, the company business, cooperation) are turning to the emerging crops. Here is the pure discount amount crop on per unit area: corn > vegetables > potatoes > other crops > sweet potatoes > fruit garden > paddy.Part two: Spatial Distribution Characteristics of Pollution Load of Crop Farming and driving factors.(1)The pollution load caused by fertilizer in study area is quite high, reaches to 3.54t?km-2;(2)The spatial distribution of pollution load caused by crop farming varies a lot in research area, and it closely related to the farming variety and distribution;(3)The closer the farming area to the downtown, the heavier the pollution load, showing the distribution characteristics of “class-point source”;(4)The crop type index, proportion of agricultural workers, unit value of arable land and farmland conversion rate have significant impact on pollution load amount, TN and TP; and other factors have positive impact on pollution load amount, TN and TP except cultivated land circulation.Part three: Characteristics of non-point source pollution load of crop farming(1)The current farmland pattern shows a trend of diversification as self-cultivation, cropland transfer and fallow in the sample region. Dynamic characteristics of cultivated land present a special feature that is more “transfer-into” than “transfer-out”. Various scales of planting are represented among the various households, according to the following decreasing order: half-labor household > non-labor household > adequate labor household;(2)The highest pollution loading produced by crop farming occurs in half-labor households while the lowest occurs in non-labor households. With increasing labor,, the pollution load per unit area tends to first increase and then decrease within families with enough labor;(3)As the type of livelihood transitions from agriculturally dominant to non-agriculturally dominant, the maximum reduction of total pollution loading produced by the agricultural industry can reach 72.01%. Compared to agriculturally dominant livelihoods, multiple-type livelihoods produce a pollution load reduction yield of 19.61%~29.85%, and non-agriculturally dominant livelihoods reduce the pollution load yield by 35.20%~72.01%. However, the rate of reduction of total nitrogen is not the same as total phosphorus;(4)The non-agricultural characteristics of labor allocation and income promote the transformation from dominant livelihood types to non-agricultural livelihoods, while potential revenue conversion follows a similar trend. In addition, different household types do not display identical conversion rates, according to the following decreasing order: enough labor household > half-labor household > non-labor household;(5)During rapid urbanization and the building of new industrial systems, the livelihood types of rural households have been further transformed to non-agricultural household types in the mountainous region; his process will lead to the further reduction of pollution load generated by planting and agriculture. Hence, significant decreases in the planting pollution load necessitate the development of control measures to enhance transformations from agricultural to non-agricultural livelihoods.