半干旱区南果梨秸秆覆盖蓄水保墒技术研究

在辽西半干旱区,南果梨树盘覆盖秸秆能够提高土壤含水量和果树产量。随着秸秆覆盖厚度的增加土壤蓄水保墒能力逐渐增强,产量不断提高,但是厚度超过25cm后,作用效果不再明显增强。在5个水平中,覆盖厚度为30cm和25cm与其它三个处理相比,增产显著,但二者之间的差异不显著。因此,南果梨覆盖栽培中适宜的秸秆覆盖厚度为25cm左右。     

Effects of elevated CO2 concentration,irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas

In this paper, we discuss the effect of elevated CO₂ concentration, irrigation and nitrogenous fertilizer application on the growth and yield of spring wheat in semi-arid areas. A field experiment was conducted at the Dingxi Agricultural Experiment Station during 2000–2002. According to the experimental design, the CO₂ concentration increased to 14.5, 40 and 54.5 μmol mol⁻¹, respectively, by NH₄HCO₃ (involving CO₂) application, direct application of CO₂ gas and combination of fertilizer NH₄HCO₃ plus CO₂ application, which are equal to CO₂ concentration of the Earth's atmosphere in the next 5, 15 and 20 years. The fertilizer application was divided into three levels: application of NH₃NO₃ (250 kg h m⁻²), NH₄HCO₃ (500 kg h m⁻²) and no fertilizer. Irrigation was divided into two levels: with 90 mm irrigation in the growth period and without irrigation. They can be combined as eight treatments. Each treatment was replicated three times. The results showed that elevated CO₂ concentration owing to CO₂ application leads to remarkable increase in leaf area index (LAI) and shoot biomass, and also generates the higher value of leaf area duration (LAD) that can benefit the photosynthesis in the growth stage and yield increase in crop compared than the no CO₂ application treatment. When CO₂ concentration elevated by 14.5, 40 and 54.5 μmol mol⁻¹ with irrigation and fertilization, correspondingly, the grain yield increased by 6.3, 13.1 and 19.8%, respectively, whereas without irrigation and fertilization, the grain yield increased by only 4.2% when CO₂ concentration increased to 40 μmol mol⁻¹. Meanwhile, irrigation and fertilization can result in larger and deeper root system and have significantly positive influences on higher value of root/shoot (R/S) and water use efficiency. The grain yields in irrigation, irrigation plus NH₃NO₃ application and irrigation plus application of NH₄HCO₃ treatments are 73.4, 148.0 and 163.6% higher than that of no-irrigated and no-fertilized treatment, suggesting that both irrigation and fertilizer application contribute to remarkable increase of crop yield. In all treatments, the highest water use efficiency (WUE, 7.24 kg h m⁻² mm⁻¹) and grain yield (3286 kg h m⁻²) consistently occurred in the treatment with 90 mm irrigation plus fertilizer NH₄HCO₃ and elevated CO₂ concentration (54.5 μmol mol⁻¹), suggesting that this combination has an integrated beneficial effect on improving WUE and grain yield of spring wheat. These results may offer help to maintain and increase the crop yields in semi-arid areas.     

不同藜麦品种在东乡半干旱区的适应性表现

为探明不同藜麦品种在东乡地区的适应性与丰产性表现,以期筛选出适合东乡地区种植推广的藜麦品种,对引进和自育的14个藜麦品种在东乡不同生态区进行了适应性试验,结果表明,在老庄村试点,品种陇藜1号(CK)表现出良好的抗倒伏性与丰产性,陇藜5号表现出良好的抗倒伏性与较好的丰产性;在米家村试点和南阳洼村试点,陇藜5号均表现出良好的抗倒伏性与丰产性。陇藜5号表现出优异的早熟特性,籽粒品相也优于陇藜1号。综合评价认为,陇藜5号在东乡半干旱地区具有更高的推广价值。     

回归等值线图在分析旱地蔬菜全生育期土壤水分动态变化规律中的应用

为了探究半干旱地区不同作物布局中种植甘蓝的耗水特征,本试验引入玉米、谷子、菜豆、大豆、马铃薯与甘蓝构建三年轮作系统,设置8种轮作组合,利用回归等值线图分析不同轮作方式处理下甘蓝全生育期土壤水分动态变化规律的差异。结果表明:以甘蓝为当年生作物附以不同的前茬处理,前一年茬口的不同对当年生甘蓝全生育期土壤含水量动态变化的影响较大,在各时期水分贮量分布产生的差异中占主导地位,前两年茬口的不同对其造成的影响较小。前一年种植作物分别为:菜豆、甘蓝、大豆、马铃薯时,甘蓝全生育期土壤水分动态变化分别呈现:不闭合峰、斜鞍形、半鞍形、闭合峰的分布;前一年种植相同作物附以前两年不同的茬口处理,对当年生甘蓝生育期内土壤含水量的时空动态变化并未造成明显的影响。该结果对当地作物类型的选择、耕作制度及作物布局的调整具有一定的指导意义。     

辽西半干旱地区昭林六号杨人工林密度及经济效益的研究

杨树人工林密度是个争论很大的问题。初植密度不同,对林分未来产量和效益影响很大。根据营林目的确定合理的造林密度和轮伐期是杨树集约栽培中的一项重要技术措施和基本前提,它可以保证林木群体结构最大限度地利用空间,在单位面积上得到最大的生长量和经济效果。在辽宁西部半干旱区的建平县,用该区广为栽培的优良杂种无性系昭林六号杨(Populus Zhaoling 6′)进行集约栽培下的密度试验,旨在研究密度对杨树人工林生长量、林     

Long-term impact of conservation tillage on stratification ratio of soil organic carbon and loss of total and active CaCO3

Under semi-arid conditions, the properties of many soils are influenced by the presence of organic matter and calcium carbonate (CaCO₃). However, the influence of different tillage systems on the development of these properties has scarcely been studied under semi-arid Mediterranean conditions. We studied the effect of long-term conservation tillage (CT) and traditional tillage (TT) on the stratification ratio of soil organic carbon and on CaCO₃ content. The study was conducted in a wheat (Triticum aestivum L.)–sunflower (Helianthus annuus L.) crop rotation established in 1991 under rainfed conditions in Southwestern Spain. As is traditional in this area, wheat was fertilised, but sunflower was not. Conservation tillage was characterised by reduced number of tillage operations and leaving crop residues on the soil surface, while TT was with mouldboard ploughing. Stratification ratio of soil organic C was calculated from C contents in the 0–5 and 5–10 cm soil layers divided by that in the 25–40 cm. Stratification ratio of soil organic C under the CT (>2) was significantly greater than under TT (<2); values >2 indicating better soil quality. Our results show a loss of CaCO₃ under both tillage systems. However, the loss of CaCO₃ was significantly higher under TT than under CT. Also, P and K accumulated in the soil surface and stratification ratio for both nutrients was greater in CT than in TT.     

半干旱黄土丘陵区微地形变化对人工柠条林草本分布的影响

本研究在典型半干旱黄土丘陵区龙滩小流域内,以水平阶整地方式栽植柠条（Caragana korshinskii）林为研究对象,调查不同坡位柠条林下水平阶内和阶间坡面草本群落组成及生物量,确定微地形及土壤环境变化对草本分布的影响及相对贡献率。结果表明：草本地上生物量及含水量均表现为水平阶内 > 阶间坡面,不同坡位水平阶内和阶间坡面草本组成的相异性为上坡位（75.2%） > 中坡位（60.0%） > 下坡位（50.7%）。pRDA排序表明：土壤含水量、微生境和坡位解释了35.8%的坡面草本群落变异,是影响草本群落分布的主要环境因子。相关分析表明：土壤含水量与长芒草（Stipa bungeana）的重要值呈显著负相关,与茵陈蒿（Artemisia capillaris）和束伞亚菊（Ajania parviflora）呈显著正相关;草本地上生物量与草本物种丰富度、长芒草等草本重要值呈显著负相关,与茵陈蒿等草本重要值呈显著正相关;下坡位草本地上生物量的降低促进了长芒草等地带性草本的恢复。综上所述,水平阶整地提高了林下草本地上生物量,降低了草本的物种丰富度,这在中、上坡位表现尤为明显。     

新疆半干旱地区不同种类混播草地的牧草产量和营养价值研究

提高混播草地的生产力和维持其营养价值对提高新疆半干旱地区放牧家畜生产力具有重要意义。本研究选择4种牧草,以单播为对照,设置豆禾两种牧草和3种牧草进行混播,分析混播草地生产力和牧草营养价值变化。结果表明：与单播相比,混播草地不仅具有明显生物量优势,而且牧草的酸性洗涤纤维和中性洗涤纤维含量更低,粗蛋白含量、干物质消化率、干物质采食量和相对饲喂价值更高;随着生长年限的增加（2016年到2018年）,单播和混播草地牧草干物质产量、粗蛋白产量、酸性洗涤纤维、中性洗涤纤维含量均显著增加,但粗蛋白含量、干物质消化率、干物质采食量和相对饲喂价值均显著下降。     

Biodrainage potential of <Emphasis Type="Italic">Eucalyptus tereticornis</Emphasis> for reclamation of shallow water table areas in north-west India

Ground water table (g.w.t.) levels were measured twice a month for 2 years in 50 observation wells installed inside and outside the two 18-year-old and 350 m apart plantations of Eucalyptus tereticornis (Mysure gum) at Dhob-Bhali research plot located in Rohtak district of Haryana state (north-west India). Throughout the study, the g.w.t. underneath the plantations remained lower than the g.w.t. in the adjacent fields. The average g.w.t. in the plantations was 4.95 m and the average g.w.t. in the control located in adjacent fields was 4.04 m. Interestingly, the spatial extent of lowering of g.w.t. in the adjacent fields was up to a distance of more than 730 m from the edge of a plantation. Drawdown in the g.w.t. developed due to the effect of a plantation was similar to the cone of depression of a pumping well and the drawdown in the g.w.t. developed due to the joint effect of both the plantations was similar to the combined cone of depression of two pumping wells. There was no correlation between soil salinity and the g.w.t. The fluctuations in g.w.t. caused fluctuations in g.w.t. salinity in the plantation as well as in the adjacent fields, but there was no net increase in g.w.t. salinity underneath the plantation. Sinker roots of Eucalyptus tree reached the zone of capillary fringe up to a depth of 4.40 m, indicating that the Eucalyptus trees were absorbing capillary water of the g.w.t. Thus, in shallow g.w.t. areas of semi-arid regions with alluvial sandy loam soils, the plantations of E. tereticornis act as bio-pumps and therefore, we recommend closely spaced parallel strip plantations of this species for the reclamation of waterlogged areas.     

半干旱区小麦玉米雨水高效利用技术模式

根据榆中县东部半干旱农业区的特点,总结推广的旱作玉米双垄全膜覆盖集雨沟播集成技术模式可使旱地玉米平均单产比半膜覆盖增产30.4%,增加产值2345.4元/hm2;小麦微垄覆膜集雨集成技术模式可使旱作小麦的平均产量比露地常规种植对照增产25.2%,增加产值758.25元/hm2。并重点从选地整地、选用良种、起膜覆膜、田间管理等方面介绍了配套栽培技术。