China’s rice agriculture, a primary source of greenhouse gases (GHGs), has experienced great changes in the last five decades due to changes in dominant varieties and farming practices. However, the impacts of these changes on GHG emissions have not been comprehensively assessed. While most earlier studies focused on the GHG emissions per unit area, recent research indicated that the yield-scaled impact may better reflect the reality. Through integrating the results from a meta-analysis, two multi-site field experiments and an expert survey, we quantify the integrated impacts of different practices on both area- and yield-scaled GHG emissions in China. Results from the expert survey showed that rice planting area has shifted northwards, and alternate water-saving (WS) irrigation has been applied in nearly 78% of Chinese rice paddy areas in both the rice nursery stage and post-transplanting period over the past five decades. The changes of these practices and replacement of new rice varieties have increased China’s rice yield by 131%. During the same period, cropping system adjustment, variety replacement, and implementation of WS irrigation have reduced total GHG emissions by 7%, 31%, and 42%, respectively. Also, the major decrease in GWP occurred prior to the 2000s, and the decreasing trend continued in the post-2000s period but at a slower rate. Our results have some limitations as these estimates ignore a number of important variations and interactions among management factors as well as climatic and edaphic conditions. Still, our findings illustrate that it is possible to enhance rice productivity at reduced environmental costs through screening for low emission varieties and agronomic practices. Future innovations should ensure that rice farming progressively adapts to climate change, while continuing to reduce GHG emissions.

It is highly desirable to test agricultural emission mitigation strategies in a whole-farm environment to ensure that all aspects of management and production operations are included. However, the large spatial scale of commercial operations makes the dual measurements of control and treatment(s) difficult. We evaluated the application of two micrometeorological methods, a novel concentration ratio method and an inverse dispersion method, where both were used to measure methane (CH) emission reductions in cattle fed the compound 3-nitrooxypropanol compared with cattle fed just the basal diet. In total, there were 1344 cattle used that were located in six pens (∼222 animals per pen). Three adjacent pens to the east and three to the west were designated as the treatment and control blocks, respectively. Underlying the emission reduction method was the assumption of site symmetry between the treatment and control pen blocks in the feedlot. There was, on average, a large CH emission reduction of ∼70% (±18%) due to the additive as found by both micrometeorological methods. Both methods also show a change in the diel distribution (peak emissions after initial morning feeding) and seasonal pattern (a decrease in emission reduction of 7.5 and 26.1% over 90 d). The simplicity of the developed concentration ratio method is expected to have applications for evaluating other mitigation strategies at large commercial scales (e.g., the application of manure additives to pens to reduce odors and ammonia emissions).© 2019 The Author(s). Re-use requires permission from the publisher.

The objectives of these studies were to evaluate the effects of biochar (0%, 0.8%, or 3% of diet dry matter) on diet digestibility and methane and carbon dioxide production from cattle on growing and finishing diets. The growing diet consisted of 21% brome hay, 20% wheat straw, 30% corn silage, 22% wet distillers grains plus solubles, and 7% supplement. The finishing diet consisted of 53% dry-rolled corn, 15% corn silage, 25% wet distillers grains plus solubles, and 7% supplement. In both trials biochar replaced fine ground corn in the supplement. Six crossbred steers (initial body weight [BW] 529 kg; SD = 16 kg) were used in both the growing and finishing trial. The growing diets were evaluated over 6 periods followed by the finishing trial with 3 periods. Digestibility measures were taken over 4 d after at least 8 d of adaptation to diets followed by 2 d of gas emission measurements using headbox calorimeters. Dry matter intake (DMI) was not affected ( ≥ 0.43; 7.91 kg/d) by biochar inclusion in the growing study and increased quadratically ( = 0.07) in the finishing study with 0.8% biochar inclusion having the greatest DMI (12.9 kg/d). Organic matter (OM) and neutral detergent fiber (NDF) digestibility increased quadratically ( = 0.10) in the growing study whereas OM digestibility tended to linearly decrease ( = 0.13) and NDF digestibility was not affected ( ≥ 0.39) by biochar inclusion in the finishing diet. Digestible energy intake (Mcal/d) was not affected ( ≥ 0.25) by biochar inclusion in the growing or finishing study. Methane production (g/d) tended to decrease quadratically ( = 0.14) in the growing study and was decreased 10.7% for the 0.8% biochar treatment relative to the control. There were no statistical differences in methane production (g/d) in the finishing study ( ≥ 0.32) but cattle on the 0.8% biochar treatment produced numerically less (9.6%) methane than the control. Methane production as g/kg DMI of the 0.8% biochar treatment relative to the control was numerically reduced 9.5% and 18.4% in the growing and finishing studies, respectively ( ≥ 0.13). Carbon dioxide production (g/d and g/kg of intake) quadratically decreased ( ≤ 0.06) in the growing study but was not affected by treatment in the finishing study ( ≥ 0.34). Although biochar is not a U.S. Food and Drug Administration -approved feed for cattle, the initial research shows potential as a methane mitigation strategy in both growing and finishing diets.© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.

Fermentation in the rumen of cattle produces methane (CH4). Methane may play a role in global warming scenarios. The linking of grazing management strategies to more efficient beef production while reducing the CH4 emitted by beef cattle is important. The sulfur hexafluoride (SF6) tracer technique was used to determine the effects of best management practices (BMP) grazing compared with continuous grazing on CH4 production in several Louisiana forages during 1996-1998. Cows and heifers (Bos taurus) grazed common bermudagrass [Cynodon dactylon (L.) Pers.], bahiagrass (Paspalum notatum Flugge), and ryegrass (Lolium multiflorum Lam.) pastures and were wintered on bahiagrass hay with supplements of protein molasses blocks (PMB), cottonseed meal and corn (CSMC), urea and corn (URC), or limited ryegrass grazing (LRG). Daily CH4 emissions were between 89 and 180 g d(-1) for young growing heifers and 165 to 294 g d(-1) for mature Simbrah cows. Heifers on "ad lib" ryegrass in March and April produced only one-tenth the CH4 per kg of gain as heifers on LRG of 1 h. Using BMP significantly reduced the emission of CH4 per unit of animal weight gain. Management-intensive grazing (MIG) is a BMP that offers the potential for more efficient utilization of grazed forage crops via controlled rotational grazing and more efficient conversion of forage into meat and milk. Projected CH4 annual emissions in cows reflect a 22% reduction from BMP when compared with continuous grazing in this study. With the BMP application of MIG, less methane was produced per kilogram of beef gain.

植物精油(EOs)是经蒸馏等方式从植物组织中提取的易挥发油状芳香物质,具有良好的抗菌、抗氧化和抗炎活性。EOs能够提高动物机体的免疫性能并促进动物生长,被认为具有良好的替抗潜力,近年来在反刍动物上的应用逐渐广泛。本文综述了EOs对反刍动物瘤胃发酵、甲烷产量、动物生产性能、畜产品品质及机体免疫性能的影响及其作用机制,旨在为EOs在反刍动物生产中的推广应用提供理论参考。

结合当地实际情况,选择中药配方的国家发明专利(专利号:ZL201310296988.6)禾奇正中药肥,在21个不同水稻品种(系)上进行试验。结果表明,使用禾奇正中药肥可以提高每667 m²水稻的有效穗数、结实率及千粒重等相关农艺性状,从而显著增加水稻的产量,与空白对照相比增产0.6%~22.0%;同时,与空白对照相比,稻瘟病病穗率下降1.06~11.32百分点,发病指数下降4.69;水稻病穗率流行程度和病指流行程度存在较大的差异,其中病穗率流行程度均降低0~1个等级,病指流行程度差异不显著,但与其对应的发病指数显著降低。表明禾奇正中药肥不仅可以增加水稻产量,还可显著降低稻瘟病的发病率和发病指数,提高水稻品质。

为探索有机磷农药降解的新途径和方法,以大黄、海桐皮、木槿皮、五倍子按9:4:3:2质量份数混合,粉碎并以水浸泡,以GC-MS定量检测法、农残速测法,通过比较试验前后有机磷农药浓度变动,明确其对有机磷农药的降解效果。结果表明,2 min内浸提液对毒死蜱、对硫磷2种有机磷农药降解率分别达到93.6%、92.9%;浸提液17 h内对敌敌畏降解率为66.67%,11 h内对毒死蜱降解率为48.69%。本研究表明,大黄、海桐皮、木槿皮、五倍子浸提液对毒死蜱、对硫磷、敌敌畏等有机磷农药有显著降解效果。

In the fight against arthropod crop pests using plant secondary metabolites, most research has focussed on the identification of bioactive molecules. Several hundred candidate plant species and compounds are now known to have pesticidal properties against a range of arthropod pest species. Despite this growing body of research, few natural products are commercialized for pest management whilst on-farm use of existing botanically-based pesticides remains a small, but growing, component of crop protection practice. Uptake of natural pesticides is at least partly constrained by limited data on the trade-offs of their use on farm. The research presented here assessed the potential trade-offs of using pesticidal plant extracts on legume crop yields and the regulating ecosystem services of natural pests enemies. The application of six established pesticidal plants (Bidens pilosa, Lantana camara, Lippia javanica, Tephrosia vogelii, Tithonia diversifolia, and Vemonia amygdalina) were compared to positive and negative controls for their impact on yields of bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and pigeon pea (Cajanus cajan) crops and the abundance of key indicator pest and predatory arthropod species. Analysis of field trials showed that pesticidal plant treatments often resulted in crop yields that were comparable to the use of a synthetic pesticide (lambda-cyhalothrin). The best-performing plant species were T vogelii, T. diversifolia, and L. javanica. The abundance of pests was very low when using the synthetic pesticide, whilst the plant extracts generally had a higher number of pests than the synthetic but lower numbers than observed on the negative controls. Beneficial arthropod numbers were low with synthetic treated crops, whereas the pesticidal plant treatments appeared to have little effect on beneficials when compared to the negative controls. The outcomes of this research suggest that using extracts of pesticidal plants to control pests can be as effective as synthetic insecticides in terms of crop yields while tritrophic effects were reduced, conserving the non-target arthropods that provide important ecosystem services such as pollination and pest regulation. Thus managing crop pests using plant secondary metabolites can be more easily integrated in to agro-ecologically sustainable crop production systems.