Establishing white spruce in the Boreal White and Black Spruce Zone

Two trials (``Wonowon' and ``Iron Creek') in the Prince George Forest Region of interiorBritish Columbia were begun in the mid 1980s toevaluate site preparation treatments for establishingwhite spruce (Picea glauca [Moench] Voss) in theBoreal White and Black Spruce biogeoclimatic zone. The14 treatments (9 or 10 per trial) were: [B.C.]Ministry, Sinkkila, and Bracke mounds; Bracke moundsmanually supplemented with 20-, 14-, or 6-cm cappingsof mineral soil; fertilized Sinkkila mounds; Brackepatches; fertilized Bracke patches; bladed strips;plowed ground; herbicide; and untreated controls,separately with both standard and nominally superior``alternate' planting stock. With minor aberrations,each trial consists of 5 randomized complete blockseach with one 80-tree plot per treatment; planting wasin spring, 1984 at Wonowon, 1987 at Iron Creek. Alltrees in mounding treatments and the inner 48 trees inother plots were monitored for performance through1998 at Wonowon, 1996 at Iron Creek. The herbicide andplowing treatments, and mounds capped thickly enoughwith mineral soil to inhibit weed regrowth, wereclearly superior to others. In the mounding treatments at Wonowon, survival rateincreased with capping thickness, but, while the 14 and 20 cmcappings were best, significant differences among them were few after 15 growing seasons.In both trials, patchscarification gave poorer results than did plantingwithout site preparation.     

广义线性回归模型的Moore-Penrose逆阵岭估计

考虑广义线性回归模型y=Xβ+e,E(e)=0,Cov(e)=σ2Σ,当设计矩阵Xn×p呈现病态时,定义广义线性回归模型的Moore-Penrose逆阵岭估计为(k)=(X′Σ-1X+kI)+X′Σ-1y,k>0,讨论了广义线性回归模型的Moore-Penrose逆阵岭估计具有的性质.     

起垄种植与不同地膜覆盖对棉花生长发育及产量的影响

以冀优01为试材,研究了起垄种植、起垄种植＋喷液体地膜覆盖、塑料地膜覆盖以及塑料地膜＋棉花秸秆覆盖（二元覆盖）4种种植方式对棉花生长发育和产量的影响。结果表明：不同覆盖栽培方式均可提高土壤温度,增加土壤含水量,棉花出苗期提前,产量也有大幅度提高;二元覆盖效果最明显,棉花生育期较其他处理提前4～5d,籽棉产量和皮棉产量分别比对照提高5．2％和6．2％;起垄种植对棉花生长发育及产量影响效果不显著。     

渭北旱原夏闲期麦田不同耕作措施的土壤贮水效应

【目的】研究免耕、深松和翻耕麦田夏闲期土壤贮水能力,揭示3种耕作方式麦田土壤蓄水保墒能力产生差异的机理。【方法】选取渭北旱原中等产量水平的旱作麦田,于2007和2008年麦田夏闲期,研究免耕、深松和翻耕3种耕作方式下,麦田0~300 cm土层土壤贮水量和降雨后土壤水分的时空变化特征。【结果】2007和2008年夏闲前后,免耕、深松处理0~300 cm土层土壤含水量较翻耕处理分别提高47.2%,55.6%和38.9%,22.2%,均达到显著水平(P<0.05),并且3种耕作方式土壤贮水量的差异主要体现在160或140 cm以上土层;免耕和深松土壤贮水效果总体优于翻耕处理,但免耕和深松处理在2007和2008年的土壤贮水效果有一定差异,前者深松优于免耕,差异不显著,而后者免耕显著优于深松;夏闲期<10 mm降雨后3,7和13 d,免耕和深松土壤0~100 cm土层含水量均高于翻耕农田,而免耕和深松土壤水分的差异主要出现在降雨后7 d;10~30 mm降雨后7 d,免耕和深松土壤0~200 cm土层含水量明显高于翻耕土壤,但在降雨后1和3 d无显著差异。【结论】夏闲期免耕和深松耕作方式较翻耕方式显著提高了土壤的贮水能力,其机理主要在于免耕和深松耕作方式增强了降雨后土壤的蓄水保墒能力。     

The tillage effect in sustaining soil functions

This paper examines how alteration of soils by tillage changes the sustainability of soil functions. Soil tillage presents an enigma in thinking about soil sustainability in ecosystems. There is a several‐thousand‐year history of gradually increasing the disturbance of ever‐greater volumes of soil. The dominant concept was that these changes by tillage increased crop production. We now have a several‐decade concern with decreasing tillage, both for reasons of economy and sustainability. Have soil conditions changed, or do we now know more about soil science and its application to crop production? Specific soil uses, specific soils, characteristics of the site, and whether short or long‐term changes are being evaluated determine the effects of tillage in agro‐ecosystems. The largest effects of tillage are increased recycling rates and long‐term decreases in porosity and in diversity of habitat. The benefits of tillage in annual crop production appear to be a temporary improvement of water and oxygen conditions in a seedbed, and the destruction of competing plant species. Environmental concerns such as water quality, diversity of habitat, storage of carbon and nitrogen, and water partitioning are negatively affected by tillage.     

菜豆的节水技术研究

研究不同灌溉方式、不同农艺措施对菜豆生长和水分利用效率的影响,为菜豆生产寻找高效节水技术措施。滴灌能明显降低耗水量,比畦灌节水30%,耗水强度也明显降低,菜豆产量和水分利用效率均显著提高,增产25.5%,水分利用效率提高35.6kg/mm.hm²。在畦灌条件下,不同农艺措施之间耗水总量和耗水强度差异不大,但产量和水分利用效率差异较大。施用抗旱剂、保水剂的菜豆产量及水分利用效率显著高于对照,增产分别达25.2%和18.6%,水分利用效率分别提高14.0kg/mm.hm²和11.1kg/mm.hm²。菜豆根瘤菌生长发育状况在不同处理之间有一定差异。     

玉米垄作免耕播种机油耗试验与分析

保护性耕作技术在我国垄作地区难以推广的主要原因是缺乏在有根茬原垄上确保播种质量的免耕播种机。针对以苗带浅旋处理玉米根茬为机理的2BML-2型垄作免耕播种机,进行了田间油耗试验。试验结果表明:在开沟器、覆土装置、镇压装置等部件工作参数一定时,影响播种机油耗的主要因素中,根茬处理装置的旋耕入土深度影响最大,其次是旋耕幅宽,然后是机组前进速度;在适合范围内,机组前进速度越大,油耗越小;本播种机能有效减少油耗,传统旋耕播种与之相比,油耗量高32%以上。通过建立油耗数学模型,可以较准确计算出在所给定的条件和工况范围内的单组油耗量,同时可为选择合适的作业参数及设计同类型播种机提供理论指导。     

贵州喀斯特山区旱地绿肥聚垅秸秆还土的培肥增产效应研究

在贵州喀斯特山区黄壤和石灰土上进行定位试验 .研究结果表明 ,绿肥聚垅、秸秆还土和绿肥聚垅 +秸秆还土均能在一定程度上提高土壤有机质及养分含量 ,改善土壤物理性状 ,提高土壤肥力 ;促进作物 (特别是玉米 )生长发育 ,改善作物经济性状 ,提高产量 ,各处理的年平均粮食复合产量比对照增加36 .3～ 1 1 7.0kg/ 6 6 7m2 ,增加 5.6 8%～ 2 0 .97% .其培肥增产作用明显     

Effects of farmyard manure and tillage systems on soil physical properties and corn yield in central Iran

Tillage management and manure application are among the important factors affecting soil physical properties and crop yield. A 2-year field experiment was conducted on a silty clay loam soil (fine-loamy, mixed, thermic Typic Haplargids). Effects of two tillage systems (moldboard plowing as conventional tillage (T₁) and disk harrowing as reduced tillage (T₂)) at three farmyard manure rates (zero (M₁), 30 (M₂), 60 (M₃) Mg ha⁻¹) were studied on the soil physical properties and corn (Zea mays L.) yield. The experiment was carried out in split block design with three replications. Organic matter (OM) content, bulk density (BD), saturated hydraulic conductivity (K_S), aggregate mean weight diameter (MWD) and dry biomass yield (DBY) were measured after harvesting in the second year. Manure application increased OM on both the row and inter-row tracks significantly. Manure application rate of 60 Mg ha⁻¹ increased MWD (0.33, 0.40 and 0.75 mm for M₁, M₂ and M₃, respectively) at the 0–5 cm soil layer, but the effect was not significant below 5 cm depth. Adding manure significantly decreased soil BD on the row tracks (1.39, 1.22 and 1.17 Mg m⁻³ for M₁, M₂ and M₃ treatments, respectively), but did not have any significant effect on the inter-row tracks. Hydraulic conductivity was improved by manure applications both on the row and inter-row positions. Manure treatments M₂ and M₃ increased DBY compared to the M₁ treatment. Although moldboard plowing increased the depth of root penetration significantly (43 cm for T₁ and 30 cm for T₂), the effect of tillage systems on yield and soil physical properties was not significant.     

Wind tunnel simulation of ridge-tillage effects on soil erosion from cropland

In the arid and semi-arid regions, ridge tillage was often used as an alternative practice for wind erosion control on the croplands without sufficient crop residues left during the fallow period. Through wind tunnel experiments, wind erosion rate and vertical mass flux profile of blown sand under the simulated conditions of ridge tillage and flat tillage were studied in 15, 10, 10, 5, 3 min exposures at the wind velocities of 8, 10, 15, 20, 24 m s⁻¹, respectively. The results for the soil tested indicate that the mean rate of wind erosion under flat tillage was 129.89 g m⁻² min⁻¹, while that under ridge tillage were 20–60% less. Under ridge tillage with different structures, average wind erosion rate had a positive correlation with the spacing between adjacent ridges. For the same ridge height, average wind erosion rate decreased with increasing ratio between the height of ridge and the width of furrow. For the same ratio between the height of ridge and the width of furrow, average wind erosion rate increased with increasing height of ridge. Power function relationships were found between wind erosion rate and wind velocity on all the simulated tillage conditions. A wind velocity of 15 m s⁻¹ was the critical velocity, above which wind erosion rate increased rapidly for the soil and simulated tillage conditions tested. Compared with flat tillage, ridge tillage remarkably decreased wind erosion rates when wind velocities were beyond 15 m s⁻¹. Under ridge tillage, the total mass of sand transported at a height of 0–20 cm above soil surface (Q_0–20), and the fraction of that travelling at a height of 0–4 cm (Q_0–4/Q_0–20), were less man mat under flat tillage. For the same ridge height, Q_0–4/Q_0–20 increased with increasing ratio between the height of ridge and the width of furrow. For the same ratio between the height of ridge and the width of furrow, Q_0–4/Q_0–20 decreased with increasing height of the ridge. Sand transport rate under flat tillage decreased with increasing height by a negative exponential function, while negative linear functions were found under ridge tillage. Thus ridge tillage decreased the rate of wind erosion and sand transportation near soil surface, reduced the loss of soil nutrient caused by wind erosion and plant damage caused by blown sand abrasion, which make it an effective agricultural technology for wind erosion control in the arid and semi-arid regions.