Acidification of a solonetzic soil by nitrogenous fertilizers

Abstract

Annual applications of (NH₄)₂SO₄ NH₄NO₃ and urea on a Solonetzic soil at 112 kg N/ha for 10 consecutive years reduced pH levels from 5.6 for the check to 4.4, 4.9 and 5.3, respectively for (NH₄)₂SO₄, NH₄NO₃ and urea. (NH₄)₂SO₄ generated twice as much exchange acidity as NH₄NO₃ and four times as much as urea. Net extractable cations leached from the Ap horizon closely approximated the amount of exchange acidity generated by (NH₄)₂SO₄ and NH₄NO₃ fertilizers. The levels of soil extractable Al and Mn were greatly enhanced by (NH₄)₂SO₄ as were plant contents. Similar acidifying effects to that produced by the (NH₄)₂SO₄ occurred when NH₄NO₃ was applied at 300 kg N/ha annually for 12 consecutive years in another field experiment on the same soil. Liming samples of the field (NH₄)₂SO₄ acidified soils in the greenhouse, significantly increased yields and lowered the Al and Mn contents of the plants to normal levels.     

有机营养肥料研究进展

对几种常用的有机营养肥料(腐殖酸、核酸及其降解物、氨基酸)的生产及其对土壤的作用和生物效应等作了综述并对有机营养肥料的研究和发展方向及其在未来的生态农业和绿色食品生产中的重要性和应用前景作了展望。     

Inhibition of nitrification in soil by metal diethyldithiocarbamates

IntroductionNitrificationisaprocessinwhichammoniumformofnitrogenisconvertedintonitrateform .Nitrogenuseefficiencyintermsofplantuptakeisgenerallylowandvariesgreatlyunderdifferentsoilandcroppingconditions.MostfertilizerNappliedtosoilsisintheformofammonium orammoniumproducingcompoundssuchasurea,andisusuallyoxidizedrapidlytonitratebynitrifyingmicroorganismsinsoils.Applicationofnitrogenfertilizersmorethanoptimumlevelsleadstolownitrogenrecoveriesandgreaternitrogenaccumulationinthesoilprofile .Theac…     

蔬菜施用环保液体有机肥的效果

城市餐饮垃圾经发酵处理生成的环保液体有机肥,在蔬菜上使用效果显著,菜心增产比常规施肥增产22.5%~26.3%,青瓜增产5.0%~15.0%。环保液体有机肥可以替代常规肥料作蔬菜的追肥。     

Herbicides interactions with cow manure and field soil organic matter

The direct interaction of the herbicide metazachlor ‐chosen as an example‐ with the soil organic matter has been studied by laboratory incubation of old and young cow manures containing metazachlor. The extraction efficiencies of solvents of increasing polarities indicated the formation of association compounds by bonds weaker than covalent between metazachlor and the organic matter: electron donor‐acceptor complexes, hydrogen bonding complexes, and complexes by both bonding types. Laboratory incubation of metazachlor in soil of low organic matter content indicated that the soil mineral part only had a diluting effect on the soil organic matter capacity to adsorb metazachlor. Similar association compounds were observed in the soil of a cauliflower field crop. Their concentrations were greater in the plots treated with organic fertilizers than in the organic fertilizers untreated plots. The free‐ unbound metazachlor was faster metabolized than the one bound to the soil organic matter, explaining why the organic fertilizer treatments slow down the herbicide soil biodegradation during the main first crop period. Inclusion of metazachlor in the field soil humic acids lattice ‐another kind of herbicide association compound with the soil organic matter‐ occurred at crop end when most of the metazachlor was metabolized; the soil concentrations of this kind of association compound thus was low, so that the release after crop of metazachlor in the environment has no practical significance.     

农业环境污染认知情况及其影响因素的实证分析研究

现代石油农业在取得巨大经济社会效益的同时,生产中化肥、农药的过度使用也引发了严重的环境问题.以中国综合社会调查(CGSS2010)的数据为基础,运用多元线性回归模型分析环境污染认识情况及其影响因素.结果表明,居民对农业环境污染认知处于高认可水平;个体的户口、年龄,社会经济地位的个人年收入和受教育年限,环境感知的环境问题严重程度、环境问题关注程度显著影响居民农业环境污染认知.提出通过引导居民形成高度的环境保护意识来改善农业生产环境,确保食品安全.     

Health Risks Associated with Predicted Increase of Cadmium in Cultivated Soils and in the Diet

We have assessed the change of the dietary intake and the potential health risks of cadmium in Finland, assuming that a high level of cadmium in fertilizers (138 mg Cd/kg P) would prevail for the next 100 years. Soil measurements and modelling were used to derive the predicted level of cadmium in foods. In three important cultivars, wheat, potato and sugar beet, the cadmium concentration would increase by 20–35%. Consequently, the average dietary intake of cadmium in Finland would increase from 7.9 to 10.0 μg/day, corresponding with the urinary level of about 0.2 μg/l, a level that has not been associated with effects on the human health. However, in the risk group with 1) high dietary intake of cadmium, 2) elevated gastrointestinal absorption, and 3) tobacco smoking, the estimated urinary level of cadmium would be 2.0 μg/l. Recent epidemiological studies have shown that urinary level of 1–2 μg Cd/l is associated with an increased risk of bone demineralization and fractures, and 2–4 μg Cd/l with pre-clinical kidney damage. People characterized by more than one of the above-mentioned risks factors, may develop the adverse health effects at an old age, when cadmium has accumulated in the body.     

Cadmium in aquatic ecosystems in Western Australia: A legacy of nutrient-deficient soils

More than 273 tonnes of cadmium have been added to Western Australian ecosystems through the application of superphosphate fertilisers since 1982. Fifty percent of this is water soluble and therefore eventually leaches into waterbodies and accumulates in the sediments. From this source, it enters the food web through algae and benthic animals and may ultimately be passed to humans. This is reflected in the cadmium levels of the freshwater mussels (Westralunio carteri) that exceeded statutory Australia New Zealand Food Authority (ANZFA) guidelines for Maximum Permissible Concentrations (MPCs) with respect to human consumption. The cadmium levels bioaccumulated in freshwater mussels elevated with increasing catchment clearing, being highest in degraded catchments. The MPC for Cd in crustaceans have recently been removed, yet tissues within the freshwater crayfish (Cherax tenuimanus) frequently exceeded the old MPC (0·2 μCd g⁻¹wet weight). Marron are sometimes consumed in considerable quantities and the risk to human health posed by a high Cd intake is briefly summarised. Finally, a number of management options concerned with reducing the level of Cd from fertilisers passing to humans are reviewed.     

Reduction in global habitat loss from fossil-fuel-dependent increases in cropland productivity

Terrestrial biodiversity loss and climate change, driven mainly by loss of habitat to agriculture and fossil fuel (FF) use, respectively, are considered among the world's greatest environmental threats. However, FF-dependent technologies are currently essential for manufacturing synthetic nitrogen fertilizers (SNFs) and synthetic pesticides (SPs) critical to increasing agricultural productivity, which reduces habitat loss. Fossil fuel use increases CO₂ levels, further enhancing agricultural productivity. Based on estimates of global increases in yields from SNFs, SPs, and atmospheric CO₂ fertilization, I estimated that FF-dependent technologies are responsible for at least 62.5% of current global food production (GFP) from cropland. Thus, if FF use is eschewed in the future, maintaining current GFP means croplands would have to increase from 12.2% of global land area (GLA) excluding Antarctica to 32.7%. The additional 20.4% of GLA needed exceeds habitat lost currently to cropland (12.2% of GLA) and cumulative conservation areas globally (14.6% of GLA). Thus, although eliminating FF use could reduce climate change, its unintended consequences may be to significantly exacerbate biodiversity loss and indirectly increase food costs, reducing food security which, moreover, disproportionately affects the poor. Although it may be possible to replace SNFs and SPs with FF-free technologies, such substitutes have not yet been demonstrated to be sufficiently economical or efficient. In the interim, meeting global food demand and keeping food prices affordable would increase habitat conversion and food prices. These trade-offs should be considered in analyses of climate change policies.