基于SPH算法的深松铲土壤切削过程仿真及试验研究

为探明深松铲土壤切削过程中切削阻力的变化规律和了解深松铲切削土壤过程情况,基于SPH方法建立了深松铲土壤深松的有限元模型,并对其深松过程进行仿真分析。仿真结果表明:SPH法能够直观地模拟深松铲土壤切削完整过程,最大等效应力为3. 184MPa,主要集中在与深松铲接触土壤上,仿真切削阻力为3.65 k N。通过耕整地移动式田间动态试验台进行田间试验验证,得出切削阻力为3. 542 k N,与仿真结果相比误差仅为3. 05%,验证了基于SPH法进行深松铲切削土壤过程的仿真是可行的。     

饲用甜高粱剪切应力和功耗试验研究

在秸秆往复式切割试验台上,以饲用甜高粱为研究对象,以切割速度、喂入速度、秸秆含水率为试验因素,功率消耗与剪切应力作为性能检测指标,按照中心组合响应曲面设计(Central composite design,CCD)试验方案进行试验。结果表明:喂入速度对切割器试验台工作性能有较大影响;切割速度、秸秆含水率均对切割器试验台工作性能影响显著;切割器试验台工作性能的影响因素主次顺序为喂入速度、切割速度、秸秆含水率,最佳性能参数组合为喂入速度5m/s、切割速度0. 95m/s、秸秆含水率为60%。本研究旨在探索秸秆往复式切割器的工作参数与饲用甜高粱收获条件对切割特性的影响,为饲用甜高粱联合收获打捆的研究提供理论依据。     

稻谷的滚筒式气体射流冲击干燥实验研究

将滚筒式气体射流冲击干燥机应用于稻谷干燥,主要研究风温、风速及滚筒转速对稻谷干燥速率、发芽率和爆腰率的影响。结果表明:稻谷的滚筒式气体射流冲击干燥属于降速干燥,且风温对干燥速率、发芽率和爆腰率的影响显著,风速对发芽率影响明显,滚筒转速对干燥速率和干燥后稻谷的品质影响不显著。研究给出了合理的干燥工艺参数:稻谷的滚筒式气体射流冲击干燥较为合理的风温为60℃,风速为23m/s,滚筒转速为3. 5r/min。本研究为稻谷快速、优质干燥提供了一种新型的技术与装置支持。     

小麦雄性不育机理的研究进展

稳定雄性不育系的建立是杂种优势利用的前提条件,因此阐明小麦雄性不育的形成机 理是实现杂交小麦高效制种的基础理论保障。本文从生理生化,分子生物学两方面对该领域的 研究进展进行综述,旨在为深入解析小麦雄性不育机制提供参考资料和研究思路。     

乡村振兴建设中农村经济管理的创新举措

改革开放40 年以来,我国经济得到飞速发展,2017 年党十九大报告中提出了乡村振兴 战略,本文说明乡村振兴战略重要意义,在结合目前建设现状提出一些农村经济管理的创新举 措,将乡村振兴战略在新农村社会主义建设中,为我国发展打造坚实基础。     

森林抚育的技术要点及合理化建议

森林抚育是确保林业系统生态稳定的重要手段。本文阐述了森林抚育设计的概况和 技术要点,通过加强外业调查、管控施工质量、确保资金充足以及优选抚育技术几个方面着重探 讨了森林抚育的合理化建议,旨在为相关工作人员提供理论性的参考依据,推动林业经济的可 持续性发展。     

Leaf litter and crop residue decomposition in ginkgo agroforestry systems in eastern China: Soil fauna diversity and abundance,microbial biomass and nutrient release

The response of soil fauna to the litter decomposition process has received considerable attention,but this effect has not been fully examined in agroforestry systems.A 1-year in situ decomposition experiment was carried out in a pure ginkgo plantation and two ginkgo agroforestry systems using a litterbag method(11 different treatments were tested in three systems).We found that the application of different organic materials(crop residues)produced positive effects on the number of soil fauna in the ginkgo planting systems;the mixture of ginkgo leaves and corn leaves was the best performing treatment.Collembola and Acarina were the predominant groups in the litter bags and were mainly responsible for the differences among the treatments.Litter mixing promoted the abundance,richness,and diversity of soil fauna,and significant differences regarding the Shannon–Wiener index of the soil fauna were observed among the 11 treatments in July.Significantly higher soil MBC(microbial biomass carbon)and MBN(microbial biomass nitrogen)were observed in agroforestry systems than in pure ginkgo plantations.These results suggest that the practice of intercrop residue application plays an important role in enhancing soil ecosystem function in ginkgo agroforestry systems and may ultimately contribute to sustainable intercrop production,soil fertility,and local economic diversity.     

Assessing soil extracellular DNA decomposition dynamics through plasmid amendment coupled with real-time PCR

Journal of Soils and Sediments - Determining soil extracellular DNA decomposition dynamics is essential to assessing lateral gene transfer possibility, nutrient-cycling efficiency, and the...     

Residue retention mitigated short-term adverse effect of clear-cutting on soil carbon and nitrogen dynamics in subtropical Australia

Purpose

This study aimed to investigate the benefits of retaining harvest residues on the dynamics of soil C and N pools following clear-cut harvesting of a slash pine plantation in South East Queensland of subtropical Australia.

Materials and methods

Immediately following clear-cut harvesting, macro-plots (10?×?10 m) were established on a section of the plantation in a randomised complete block design with four blocks and three treatments: (1) residue removal (RR₀), (2) single level of residue retention (RR₁) and (3) double level of residue retention (RR₂). Soils were sampled at 0, 6, 12, 18 and 24 months following clear-cutting and analysed for total C and N, microbial biomass C (MBC) and N (MBN), hot water–extractable organic C (HWEOC), hot water–extractable organic N (HWEON), NH₄⁺–N and NO_x^?–N.

Results and discussion

The study showed that although soil total C decreased in the first 12 months following clear-cutting, harvest residue retention increased soil total C and N by 45% (p?<?0.001) and 32% (p?<?0.001), respectively, over the 12–24 months. NH₄⁺–N, HWEOC, HWEON and MBC showed initial surges in the first 6 months irrespective of residue management, which declined after the 6th month. However, residue retention significantly increased HWEOC and HWEON over the 12–24 months (p?<?0.001).

Conclusions

This study demonstrated that harvest residue retention during the inter-rotation period can minimise large changes in C and nutrient pools, and can even increase soil C and nutrient pools for the next plantation rotation.

     

Short-term carbon and nitrogen dynamics in soil,litterfall and canopy of a suburban native forest subjected to prescribed burning in subtropical Australia

Purpose

This study aimed to understand the mechanisms of the variations in carbon (C) and nitrogen (N) pools and examine the possibility of differentiating the burning effects from seasonal and pre-existed N limitations in a native suburban forest ecosystem influenced by prescribed burning in subtropical Australia.

Materials and methods

Soil and litterfall samples were collected from two study sites from 1 to 23 months since last burnt. Soil labile C and N pools, soil C and N isotopic compositions (δ¹³C and δ¹⁵N), litterfall mass production (LM), and litterfall total C, total N, δ¹³C and δ¹⁵N were analysed. In-situ gas exchange measurements were also conducted during dry and wet seasons for Eucalyptus baileyana and E. planchoniana.

Results and discussion

The results indicated that labile C and N pools increased within the first few months after burning, with no correlations with climatic factors. Therefore, it was possible that the increase was due to the burning-induced factors such as the incorporation of ashes into the soil. The highest values of soil and litterfall δ¹⁵N, observed when the study was commenced at the experimental sites, and their high correlations with climatic factors were indicative of long-term N and water limitation. The ¹³C signals showed that soil N concentrations and climatic factors were also two of the main factors controlling litterfall and foliage properties mainly through the changes in photosynthetic capacity and stomatal conductance.

Conclusions

Long-term soil N availabilities and climatic factors were the two of the main driving factors of C and N cycling in the studied forest sites. Further studies are needed to compare soil and litterfall properties before and after burning to profoundly understand the effects of prescribed burning on soil labile C and N variations.