拖拉机耕深自动监测与控制

拖拉机耕深采用伺服和微机根据负荷及耕深的大小进行自动控制,使拖拉机处于最佳工况,提高作业质量和经济性。由耕作阻力的力信号和耕深变化的位移信号相叠加并和设定耕深相比较输入伺服放大器或计算机,然后输出控制信号,控制电液伺服阀的工作,改变控制阀的行程和方向,以改变输入拖拉机提升油缸的油量和流向,达到控制耕深的目的。 所组成的 TMD-1 型微机拖拉机耕深控制系统成功地进行了模拟试验和田间试验,取得了满意的结果。     

Effects of alternative tillage systems on soil quality and yield of spring cereals on silty clay loam and sandy loam soils in the cool, wet climate of central Norway

Tillage trials were established on a poorly drained silty loam overlying silty clay loam and on a freely drained sandy loam overlying medium sand, in 1988 and 1989, respectively. Autumn and spring ploughing and two ploughless systems were compared for 12–13 years, with three replications at each site. The ploughless treatments comprised deep versus shallow spring harrowing until 1999, and thereafter autumn plus spring harrowing versus spring harrowing only. In 6 years, treatments with and without fungal spraying of the cereal crops were included. In other years, fungicides were not used. Perennial weeds were controlled by herbicides as necessary, on nine occasions up until 2001. Average spring barley (Hordeum vulgare L.) and spring oat (Avena sativa L.) yields were similar with spring ploughing as with autumn ploughing at both sites. In treatments without ploughing, average yields on the silty loam over clay were 93% of those obtained with ploughing, and on the sandy loam over sand they were 81%. Smaller and non-significant yield differences were found between spring harrowing versus deep spring harrowing, and between autumn plus spring harrowing versus spring harrowing only. Fungal spraying increased yields markedly at both sites (25%), but there was no significant interaction between this treatment and tillage system. Oat was compared with barley in 2 years, with oat performing better under ploughless tillage. At both sites increases in penetrometer resistance occurred in the topsoil of unploughed treatments. These were considered particularly limiting on the sandy loam. On the silty loam there was an increase in surface horizon porosity in the absence of ploughing, which was associated with an increase in topsoil organic matter content. On this soil there was also a tendency toward lower penetrometer resistance at >30 cm depth on autumn plus spring harrowed soil than on ploughed soil, indicating that the plough pan may have diminished. This was supported by observations of greater earthworm activity on unploughed soil. Soil chemical analyses revealed that mineral N and plant-available P and K accumulated in the upper horizon under ploughless tillage. The percentage yields obtained in individual years with autumn as opposed to spring ploughing, were positively correlated with air temperature during 0–4 weeks after planting on the silty loam, and with precipitation during 0–12 weeks after planting on the sandy loam. In the case of yields obtained with spring harrowing only, relative to spring ploughing, positive correlations were found with 0–4 week temperature on both soil types, suggesting that low early season temperatures may limit yields under ploughless tillage.     

Agricultural studies of GM maize and the field experimental infrastructure of ECOGEN

Within the ECOGEN project, long-term field experiments with genetically modified maize, Zea mays L. were conducted to study agro-ecological effects on the soil fauna and agro-economic implications of the technology. Here, we describe the study-sites, experimental layout and results of agro-economic relevance. Experiments were conducted during 2002–2005 in Denmark (Foulum), northern France (Varois) and the Midi-Pyrenees region of southern France (Narbons). MON810 Bacillus thuringiensis (Bt)-varieties expressing the Cry1Ab protein, and a T25 glufosinate-ammonium (Basta) tolerant variety expressing the pat-gene encoding phosphinotrinacetyl-transferase were compared with near-isogenic non-Bt varieties, and conventional maize varieties. At Foulum, the maize was harvested for silage. There were no significant differences in yield between Bt-maize and a near-isogenic non-Bt variety, while a small difference in N-concentration of dry matter was detected in 1 year in a range of a measured quality parameters. Similar yield and quality were found in ploughed and reduced tillage treatments in all varieties. At Varois, the maize was harvested at ripeness and no significant differences in grain yield between Bt-maize and near-isogenic non-Bt varieties were found. These results were expected, as only Narbons harbours significant corn-borer populations. At Narbons, the number of Sesamia and Ostrinia corn-borer larvae were significantly lower in the Bt-maize than in a near-isogenic non-Bt variety and for Sesamia even less than in conventional varieties sprayed with pesticides to control corn-borer infestation. Here, Bt-maize produced a higher grain yield and grain size than a near-isogenic non-Bt variety or allowed a significant reduction in pesticide use. Concentrations of Cry1Ab in the Bt-varieties were sufficient to effectively control corn-borer larvae. In soil, Cry1Ab was close to the limit of detection and the protein did not accumulate in the soil year on year.     

试论中国犁耕技术进步的推动力

犁是中国传统农具中最具代表性的生产工具。犁耕技术的发展、进步,与生产力的进步和社会制度的更迭、历代统治者的重农与革新、土地利用方式的增加、相关行业技术的进步、人口迁移与生产环境的变化、科技文化交流与民族文化交融等有着非常密切的关系。正是这些因素的推动,使我国古代犁的形制一次次改变,犁耕技术一次次取得重大突破,犁在社会发展和农业生产中的作用一次次提升。     

亚热带典型地貌下旱地和水田可溶性有机物化学组成特征

阐明亚热带典型地貌下旱地与水田土壤可溶性有机物(DOM)化学组成差异可为农田土壤DOM稳定性评价提供理论依据。研究采用XAD-8树脂分组和热裂解气质联用仪(Py-GCMS)技术,分析比较休闲期、耕作期亚热带喀斯特山区、丘陵区及平原湖区旱地和水田土壤DOM化学组成特征。结果表明:休闲期,亲、疏水性可溶性有机碳(DOC)含量以水田(10.2、33.4 mg/kg)显著高于旱地(4.15、12.8 mg/kg),耕作期无显著性差异。与休闲期相比,耕作期水田亲、疏水性DOC含量均显著降低,而旱地亲、疏水性组分DOC含量在两个时期间保持相对稳定。休闲期旱地和水田土壤DOM中有机酸相对比例分别为31.9%、35.6%,耕作期显著降至17.9%、20.0%(P0.05)。脂类相对比例趋势与有机酸相反,旱地和水田土壤DOM中脂类相对比例在休闲期分别为55.0%、49.5%,耕作期显著增至70.1%、62.9%(P0.05)。Adonis分析表明,亲、疏水性DOC含量在旱地和水田、休闲期和耕作期差异显著(P0.05);DOM化学组成在不同时期(休闲期和耕作期)及地貌(喀斯特山区和丘陵区、丘陵区和平原湖区)差异显著(P0.05)。Random Forest分析表明,有机酸和脂类参与微生物代谢过程,在休闲期和耕作期差异显著(P0.05);芳香化合物作为DOM稳定性组分,在不同地貌区差异较大(P0.05)。总体上,田间条件下水田DOC比旱地DOC对时期响应更敏感,且土壤DOM中微生物代谢相关组分(有机酸、脂类)和稳定性组分(芳香族化合物)在不同时期及地貌区的差异性不同,这对评价旱地和水田土壤DOM稳定性及土壤有机碳积累具有一定的参考意义。     

Type and time of autumn tillage with and without herbicides at reduced rates in southern Sweden: 2. Weed flora and diversity

The design of integrated weed management (IWM) systems is essential in order to reduce the use of herbicides for crop production. By combining different weed management practices, herbicides may be used at lower doses than normally recommended, while still maintaining acceptable weed population levels. The purpose of this study was to develop tillage strategies, with and without herbicides at reduced rates, appropriate for different weed populations. The influences of type and time of stubble cultivation, harrowing and mouldboard ploughing on the weed flora were followed during 1988–1994 in eight long-term field trials situated in southern Sweden. Spring-sown barley (Hordeum distichon L.) and oats (Avena sativa L.) dominated the crop rotations. Herbicides were either omitted or used at ca. 50% of a full dose. The perennial species Sonchus arvensis L. was favoured by omittance of ploughing but was better controlled by late ploughing not preceded by stubble cultivation; the reduction in the latter treatment being 74%. Stubble cultivation succeeded by ploughing reduced biomass of Elymus repens (L.) Gould. by 90% compared with ploughing solely. Early ploughing reduced the biomass of the species by 50% compared with late ploughing. The species Cirsium arvense (L.) Scop. was highly favoured by early ploughing followed by late autumn harrowing, the biomass of the species being six-fold higher than in other treatments. Compared with other treatments, stubble cultivation favoured four annuals but efficiently controlled three others, while omittance of ploughing favoured six annual and two perennial weed species. Late ploughing not preceded by stubble cultivation favoured four annual and one perennial species, while early ploughing was more efficient than late ploughing in controlling two of the annual species. Influences of treatments on weed species were frequently moderated by interspecific competition resulting in inconsistent response at different sites. Herbicides reduced the number of species by three, from 11 to eight species, averaged across sites and tillage systems. Influences of treatments on diversity were not consistent, since weed floras differed between sites and since some of the species responded inconsistently to tillage and herbicides. This study shows that by utilizing appropriate tillage strategies it is possible at many sites to maintain acceptable weed population levels, although herbicides are used at 50% lower doses than is normally recommended. The timing and type of tillage have to be chosen for being as efficient as possible to the most troublesome weed species at a site.     

Plant protection in spring cereal production with reduced tillage. II. Pests and beneficial insects

In five field experiments run for four years the infestation of pests and the activity of carabids and staphylinids were compared in autumn ploughed and reduced tillage (no-tillage or spring harrowing) plots. Differences were generally most evident in experiments with no-tillage. Weed cover was denser in reduced tillage, and could explain much of the differences. The agromyzid Chromatomyia fuscula was most common in autumn ploughed plots, probably due to healthier plants. Thrips numbers were correlated with grain quality in no-tillage plots. Field slugs were most common in reduced tillage, and were positively correlated with weed cover. Generally, more carabids and staphylinids were caught in reduced tillage. This was especially true for Amara-species and Loricera pilicornis, Philonthus cognatus and Tachinus signatus, which also were positively correlated with weed cover. Aloconota gregaria, Bembidion quadrimaculatum, B. lampros, Harpalus rufipes and Trechus quadristriatus were more common in autumn ploughed plots, several of them preferring open soil.     

刈割、耕翻与淹水集成技术控制互花米草的研究

在上海浦东东滩采用刈割、耕翻与淹水集成技术清除外来物种互花米草,以加快沿海滩涂开发垦复,增加耕地面积.研究表明:对互花米草刈割1次、耕翻4次(淹水前和淹水期间各2次),淹水1个月后互花米草的地下部分死亡并开始腐烂,互花米草得到有效控制.该技术从1月开始实施,于当年5月底结束,能够满足水稻种植的季节要求,是一种适于推广的...     

不同改良措施对盐碱化草地植被和土壤肥力的影响

通过改良试验研究，3种措施都改善了草地生境，增加土壤速效养分，增加牧草在草群中所占的比重。施肥改良使豆科和菊科牧草在草群中比重分别比对照区增加39．9％～19．8％和27．5％～34．4％，使禾本科牧草比重降低21．3％～15.3％，可食牧草产量增加22．0％～57．8％；围栏封育使豆科和菊科牧草分别增加26．7％～13．4％和4．7％～9．0％，可食牧草产量增加13．1％～78．0％。浅耕翻使豆科和菊科牧草比重分别增加27.3％～17．7％、23．2％～36.3％，禾本科牧草比重降低12．1％～10．1％，可食牧草产量增加-28．5％～28．6％。由此得出，施肥和围栏封育是草地改良的有效途径。     

Ploughing frequency and compost application effects on soil infiltrability in a cotton–maize (Gossypium hirsutum–Zea mays L.) rotation system on a Ferric Luvisol and a Ferric Lixisol in Burkina Faso

One of the key issues to increase soil productivity in the Sahel is to ensure water infiltration and storage in the soil. We hypothesised that reducing tillage from annual to biennial ploughing and the use of organic matter, like compost, would better sustain soil hydraulic properties. The study had the objective to propose sustainable soil fertility management techniques in the cotton–maize cropping systems. The effects of reduced tillage (RT) and annual ploughing (AP) combined with compost application (Co) on soil infiltration parameters were assessed on two soil types. Topsoil mean saturated hydraulic conductivities (K_s) were between 9 and 48 mm h⁻¹ in the Luvisol, while in the Lixisol they were between 18 and 275 mm h⁻¹. In the two soil types compost additions with reduced tillage or with annual ploughing had the largest effect on K_s. Soil hydraulic behaviour was in reasonable agreement with soil pore size distribution (mean values varied from 19.5 to 237 μm) modified by tillage frequency and organo-mineral fertilization. Already the first 3 years of this study showed that use of organic matter, improved soil infiltration characteristics when annual ploughing was used. Also biennial ploughing showed promising results and may be a useful strategy for smallholders to manage these soils.