The Studies On Productivity Of Different Farmland Ecosystem And Environmental Effect

Based on the location test date, the economic value, land equivalent ratio(LRE), biological yield,economic coefficient , available nutrients, soil enzyme, farmland weeds, soil respiration characteristics and environmental factors response in different rotation systems consists of food crops : wheat(Triticum aestivum), corn (Zea mays)and vegetable :garlic(Allium sativum), pepper(Capsicum), eggplant(Solanum melongena)and celery (Apium graveolens) which are common in Kuan-Chong plain were analyzed. In order to provide reference for adjustment of agricultural structure and crop arrangement which aim to improve farmers' income in the commodity economic background, optimal combination of rotation is need to be chosen reasonably in Kuan-Chong plaint. The system production efficiency and environmental effects of different rotation were comprehensly study and the optimal rotation portfolio was chosen, The results show that:1. The production efficiency of different rotation system.From the terms of economic benefit and land use, the crop rotation system composed of wheat and maize was the lowest one while the vegetables-vegetables rotation systems composed of garlic and pepper, garlic and eggplant, garlic and celery were the highest ones. From the ecological point of view, mainly focus on biological yield and net organic yield. The crop rotation system composed of wheat and maize was lower than the vegetables—vegetable rotation systems composed of garlic and pepper, eggplant, celery, but higher than the crops - vegetable rotation systems composed of wheat and pepper, garlic and eggplant, garlic and celery.The net photosynthetic rate and water use efficiency of pepper following garlic were greater than that for pepper following wheat. It suggested that, as the preceding crop of pepper,garlic was easier than wheat to raise the production ability of pepper . however, The net photosynthetic rate and water use efficiency of eggplant,celery flowing garlic were lower than that for pepper flowing wheat. It showed that ,in improving the photosynthetic efficiency of celery and eggplant,the wheat stubbly had more advantages than garlic stubbly. In terms of quality:The pepper follwing wheat had the higher content of capsaicin; The pepper and eggplant follwing wheat had the higher content of Vitamin C than that for pepper and eggplant follwing garlic; The garlic stubbly had more advantages in improving protein content of pepper and eggplant.2. The environment effect of different rotation systemThe content of organic matter, available phosphorus in different rotation system first increased , then decreased and increaed again with the growth of crops; The content of organic matter, available phosphorus were higher in garlic - celery rotation system at period of crop-rotation.while it is lower in wheat - maize rotation system at period of crop-rotation.The content of alkali-hydrolyzable nitrogen in different rotation system had a growing trend. At early period of crop-rotation, The content of alkali-hydrolyzable nitrogen was higher in garlic - celery rotation system.while it is lower in wheat - maize rotation systemat . At middle and last period of crop-rotation, The content of alkali-hydrolyzable nitrogen was higher in wheat - eggplnat rotation system.while it is lower in wheat - maize rotation systemat . The content of rapidly-available potassium in different rotation system also had a growing trend. At early period of crop-rotation, The content of rapidly-available potassium was higher in garlic - celery rotation system.while it is lower in garlic - pepper rotation systemat . At middle and last period of crop-rotation, The content of rapidly-available potassium was higher in garlic - celery rotation system.while it is lower in wheat - maize rotation systemat .The soil urease activity in wheat-maize rotation system is strongest,while it is weakest wheat - eggplant rotation system. The soil invertase activity first decreased , then increased at the period of crop-rotation. The soil invertase activity in wheat rotation system was higher than garlic rotation system. The soil catalase activity had a trend of decrease at the period of crop-rotation. The soil catalase activity in garlic -eggplant rotation system was higher than wheat-pepper rotation system.The number and kinds of weeds at early period of crop-rotation were the largest.it were smaller at middle period of crop-rotation.However, it were smallest at last period of crop-rotation. The incidence of weeds was higher in rotation system composed of celery than another rotation system. The incidence of weeds was higher in rotation system composed of garlic than that in in rotation system composed of wheat.3.The soil respiration characteristics, environmental effect and farmland carbon balance of different rotation system.The result of average CO2 emissions rate in different rotation system showed that : garlic - pepper rotation system > garlic - eggplant rotation system > wheat - pepper rotation system > wheat - celery rotation system > garlic - celery rotation system > wheat and corn rotation system > wheat - eggplant rotation system . Soil respiration rate in each rotation system had a'wave'trend that soil respiration rate first decreased and then increased. phosphorus, potassium, soil urease activity, soil temperature, soil moisture as the main factors had an effect on soil respiration rate. Through calculation of carbon balance in different rotation system, the intensity of carbon "sink" displayed as follow: garlic - pepper rotation system>wheat - eggplant rotation system >wheat- celery rotation system, wheat- maize system > garlic - celery rotation system >garlic - eggplant rotation system> wheat - celery system.According to the results of these assessments in geography condition and economic environment farmland carbon balance of diefferent rotation production, the crops—vegetable rotation system was much more suitable in field planting and production. In this study, wheat - pepper rotation mode and wheat - eggplant rotation mode had the higher advantage in improving production efficiency and keeping land productivity, improving farmland environment. those two wheat—pepper rotation mode and wheat—eggplant rotation mode had a better planting prospect.