A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromat...A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter （P 〈0.05） half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less （P 〈 0.05） than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher （P 〈0.05） moisture content, which, coupled with the likely differeaces in microbial biomass, could be the major factor responsible for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.展开更多
A new technique of dimension reduction named projection pursuit is applied to model and evaluatewetland soil quality variations in the Sanjiang Plain, Helongjiang Province, China. By adopting the im-proved real-coded ...A new technique of dimension reduction named projection pursuit is applied to model and evaluatewetland soil quality variations in the Sanjiang Plain, Helongjiang Province, China. By adopting the im-proved real-coded accelerating genetic algorithm (RAGA), the projection direction is optimized and multi-dimensional indexes are converted into low-dimensional space. Classification of wetland soils and evaluationof wetland soil quality variations are realized by pursuing optimum projection direction and projection func-tion value. Therefore, by adopting this new method, any possible human interference can be avoided andsound results can be achieved in researching quality changes and classification of wetland soils.展开更多
Both acid precipitation and unreasonable agricultural practices are notorious artificial factors resulting in soil acidification. To sort out reasonable agricultural practices favorable to abating soil acidification, ...Both acid precipitation and unreasonable agricultural practices are notorious artificial factors resulting in soil acidification. To sort out reasonable agricultural practices favorable to abating soil acidification, the task of this study was directed to a long-term field trial in Chongqing, dudng which chemical fertilizer, organic fertilizer were applied to different crop rotations and the soil pH value was measured. The results indicated that all treatments decreased pH value in the 0 to 20 cm soil layer after ten years. Problems were more serious when chlorine-containing fertilizer, excessive chemical fertilizer and mixed fertilizer were applied. It is demonstrated that balance rates of N, P and K fertilizers, application of muck in field are advantageous to abating soil acidification. Oil plants affect soil acidification more than cereal in different crop rotation.展开更多
The rationale behind the use of soil amendments by traditional marginal farmers against soil borne pathogen is an area of interest. The present work ascertain the effect of certain soil amendments against pre emergent...The rationale behind the use of soil amendments by traditional marginal farmers against soil borne pathogen is an area of interest. The present work ascertain the effect of certain soil amendments against pre emergent and post emergent rot of French bean in the agro climatic condition of Manipur, Four soil amendments： cow dung （COD）, sawdust （SD） ＋ paddy husk （PH）, decomposed floating phytomat （DFP） was tried in field conditions in four different combinations. These have been often used by the traditional farmers. A locally available commonly cultivated pole type of French bean has been used for the study. Disease incidences in plots treated with these amendments were then compared with that of control plots where no amendments were made. The plots with a combined treatment of the soil amendments showed maximum seed germination and least post emergent rot against sclerotinia rot. But DFP showed effectiveness against rhizoctonia rot with maximum seed germination while saw dust showed maximum decrease in post emergent rot against rhizoctonia rot. The plots treated with organic soil amendments showed statistically significant positive effect against the pathogens as compared with untreated control plots.展开更多
基金Project supported by the Centre for School and Community Science and Technology Studies (SACOST), University of Education, Winneba, Ghana.
文摘A field investigation was conducted to assess the breakdown of azadirachtin A in a tropical coastal savanna soil amended with neem leaves （NL） combined with poultry manure （PM） or cow dung （CD） using gas chromatography. Samples in polythene bags 15 cm long and 4.8 cm in diameter were randomly placed to a depth of 14 cm in the soil, and azadirachtin A concentration was assessed on days 0, 14, 28, 42, 56, 70, and 84. Azadirachtin A degradation in the soil followed first-order reaction kinetics with different half-lives obtained for varying combinations of the amendments. Higher neem amendment levels of 100 g gave shorter half-lives of azadirachtin A than the lower levels of 50 g. Within the 50 g NL group the additions of the poultry manure and the cow dung gave significantly shorter （P 〈0.05） half-lives of azadirachtin A than the sole neem amendment, whereas in the 100 g NL group only additions of 10 g CD and 10 g PM were significantly less （P 〈 0.05） than the sole neem amendment. Different changes resulting from the kind and quantity of animal manure added were observed in the half-lives of azadirachtin A. The 100 g NL group had significantly higher （P 〈0.05） moisture content, which, coupled with the likely differeaces in microbial biomass, could be the major factor responsible for variations in the half-llfe of the compound. Therefore, the quantity of the neem leaves applied and the addition of animal manure affected the breakdown of azadirachtin A in the soil amended with neem leaves.
基金Project supported by the China Postdoctoral Science Foundation,the Youth Foundation of Sichuan University(No.432028)and the National High-Tech Research and Development Program of China(863 Program)(No.2002AA2Z4251).
文摘A new technique of dimension reduction named projection pursuit is applied to model and evaluatewetland soil quality variations in the Sanjiang Plain, Helongjiang Province, China. By adopting the im-proved real-coded accelerating genetic algorithm (RAGA), the projection direction is optimized and multi-dimensional indexes are converted into low-dimensional space. Classification of wetland soils and evaluationof wetland soil quality variations are realized by pursuing optimum projection direction and projection func-tion value. Therefore, by adopting this new method, any possible human interference can be avoided andsound results can be achieved in researching quality changes and classification of wetland soils.
基金Funded by Key Project on Ecologic Environment Protect Plan of Chongqing (20020307)
文摘Both acid precipitation and unreasonable agricultural practices are notorious artificial factors resulting in soil acidification. To sort out reasonable agricultural practices favorable to abating soil acidification, the task of this study was directed to a long-term field trial in Chongqing, dudng which chemical fertilizer, organic fertilizer were applied to different crop rotations and the soil pH value was measured. The results indicated that all treatments decreased pH value in the 0 to 20 cm soil layer after ten years. Problems were more serious when chlorine-containing fertilizer, excessive chemical fertilizer and mixed fertilizer were applied. It is demonstrated that balance rates of N, P and K fertilizers, application of muck in field are advantageous to abating soil acidification. Oil plants affect soil acidification more than cereal in different crop rotation.
文摘The rationale behind the use of soil amendments by traditional marginal farmers against soil borne pathogen is an area of interest. The present work ascertain the effect of certain soil amendments against pre emergent and post emergent rot of French bean in the agro climatic condition of Manipur, Four soil amendments： cow dung （COD）, sawdust （SD） ＋ paddy husk （PH）, decomposed floating phytomat （DFP） was tried in field conditions in four different combinations. These have been often used by the traditional farmers. A locally available commonly cultivated pole type of French bean has been used for the study. Disease incidences in plots treated with these amendments were then compared with that of control plots where no amendments were made. The plots with a combined treatment of the soil amendments showed maximum seed germination and least post emergent rot against sclerotinia rot. But DFP showed effectiveness against rhizoctonia rot with maximum seed germination while saw dust showed maximum decrease in post emergent rot against rhizoctonia rot. The plots treated with organic soil amendments showed statistically significant positive effect against the pathogens as compared with untreated control plots.
