Switchgrass as a bioenergy crop in the Loess Plateau, China：Potential lignocellulosic feedstock production and environmental conservation

A large portion of the Loess Plateau of China is characterized as “marginal” with serious land degradation and desertification problems. Consequently, two policies, Grain for Green and Western Development Action were established by the Chinese government in response to the demand for ecological protection and economic development in the Loess Plateau. These policies are designed to increase forest cover, expand farmlands, and enhance soil and water conservation, while creating sustainable vegetation restoration. Perennial grasses have gained attention as bioenergy feedstocks due to their high biomass yields, low inputs, and greater ecosystem services compared to annual crops. Moreover, perennial grasses limit nutrient runoff and reduce greenhouse gas emissions and soil losses while sequestering carbon. Additionally, perennial grasses can generate economic returns for local farmers through producing bioenergy feedstock or forage on marginal lands. Here, we suggest a United States model energy crop, switchgrass（Panicum virgatum L.） as a model crop to minimize land degradation and desertification and to generate biomass for energy on the Loess Plateau.

Topographic differentiation simulation of crop yield and soil and water loss on the Loess Plateau

De-farming slope farmland has been an effective measure in recent years for the improvement of the eco-environment and the mitigation of soil and water loss on the Loess Plateau. This paper, taking the Yangou Basin as a case study and using day-by-day mete- orological data of Yah＇an station in 2005, simulated and analyzed the quantitative relation between crop yield, soil and water loss and topographic condition with the aid of WIN-YIELD software. Results show that： 1） topographic gradient has important influence on crop yield. The bigger gradient is, the lower the crop yield. Yields of sorghum and corn decrease by 15.44% and 14.32% respectively at 25° in comparison to the case of 0°. In addition, yields of soya, bean and potato decrease slightly by 5.26%, 4.67% and 3.84%, respectively. The influences of topographic height and slope aspect on crop yield are slight. 2） Under the same topographic condition, different crops＇ runoff and soil loss show obvious disparity. Topographic gradient has important influence on soil and water loss. In general, the changing trend is that the soil and water loss aggregates with the increase of gradient, and the maximal amount occurs around 20°. The influence of topographic height is slight. Topographic aspect has a certain effect, and the fundamental characteristic is that values are higher at the aspect of south than north. 3） Topographic gradients of 5° and 15° are two important thresholds. The characteristic about soil and water loss with the variation of topographic gradients show that： the slope farmland with gradient less than 5° could remain unchanged, and the slope farmland more than 15° should be de-farmed as early as possible.

Study on Antioxidants and Lipid Peroxidation from Pea Crops of Platean

[ Objective] The aim of this study was to discuss the effect of antioxidants and lipid peroxidation from pea crops of plateau. [ Method] SOD enzyme liquid from pea crops of plateau was extracted by means of protein concentration assay, enzyme activity assay and antioxidant activity determination by DPPH method, peroxide activity inhibition of in vitro tissues from mice by homogenate MDA colorimetry method and lipid peroxidation assay of in vitro tissues. [ Result ] IC50 of the crude enzyme liquid extracted from pea on DPPH was 55.16 mg/L, while the scavenging rate of the crude enzyme liquid was lower than that of ascorbic acid, tea polyphenol and citric acid with the same concentration. The synergistic effect was found in ascorbic acid and crude enzyme liquid, but the synergism of ascorbic acid was better than that of citric acid. IC50 of SOD enzyme liquid extracted from pea on DPPH was 11.1 mg/L, which was better than that of tea polyphenol and closely similar to that of ascorbic acid. SOD enzyme liquid extracted from pea had an inhibitory effect on MDA production from in vitro tissues such as liver, kidney and heart, especially for a significantly inhibitory effect on MDA from liver in vitro. When the concentration was 0.25 mg/ml, the inhibition rate reached 78.3%, and then the inhibition rate increased little with the concentration incresas, while its effect on heart and kidney were inferior. [ Conclusion] SOD crude enzyme liquid and SOD enzyme liquid extracted from pea all have certain DPPH scavenging capacity, while SOD enzyme liquid extracted from pea has an inhibitory effect on lipid peroxidation.

Effect of soil management on soil erosion on sloping farmland during crop growth stages under a large-scale rainfall simulation experiment

Soil erosion on farmland is a critical environmental issue and the main source of sediment in the Yellow River, China. Thus, great efforts have been made to reduce runoff and soil loss by restoring vegetation on abandoned farmland. However, few studies have investigated runoff and soil loss from sloping farmland during crop growth season. The objective of this study was to investigate the effects of soil management on runoff and soil loss on sloping farmland during crop growth season. We tested different soybean growth stages (i.e., seedling stage (R1), initial blossoming stage (R2), full flowering stage (R3), pod bearing stage (R4), and initial filling stage (R5)) and soil management practice (one plot applied hoeing tillage (HT) before each rainfall event, whereas the other received no treatment (NH)) by applying simulated rainfall at an intensity of 80 mm/h. Results showed that runoff and soil loss both decreased and infiltration amount increased in successive soybean growth stages under both treatments. Compared with NH plot, there was less runoff and higher infiltration amount from HT plot. However, soil loss from HT plot was larger than that from NH plot in R1–R3, but lower in R4 and R5. In the early growth stages, hoeing tillage was effective for reducing runoff and enhancing rainfall infiltration. By contrast, hoeing tillage enhanced soil and water conservation during the late growth stages. The total soil loss from HT plot (509.0 g/m2) was 11.1% higher than that from NH plot (457.9 g/m2) in R1–R5. However, the infiltration amount from HT plot (313.9 mm) was 18.4% higher than that from NH plot (265.0 mm) and the total runoff volume from HT plot was 49.7% less than that from NH plot. These results indicated that crop vegetation can also act as a type of vegetation cover and play an important role on sloping farmland. Thus, adopting rational soil management in crop planting on sloping farmland can effectively reduce runoff and soil loss, as well as maximize rainwater infiltration during crop growth period.

鄂尔多斯高原北部一年两季燕麦种植模式生产性能评价

为了筛选出适宜鄂尔多斯高原北部一年两季种植的优良燕麦品种,优化种植模式,以提高土地利用效率,增加经济效益,本研究分别对鄂尔多斯高原北部第一、二季种植的6个国内外燕麦品种的产量性状和营养品质进行了监测分析,并应用灰色关联度法对不同品种燕麦在该地区的生产性能进行了综合评价。结果表明,第一、二季不同燕麦品种的株高、干草产量、粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、钾(K)以及相对饲草质量(RFQ)的变化范围分别是96.77~121.77 cm、8426.38~14287.07 kg·hm^(-2)、8.19%~9.29%DM、51.47%~59.90%DM、30.00%~35.83%DM、1.23%~1.87%、117.88~161.41和68.73~97.20 cm、4927.07~7082.58 kg·hm^(-2)、12.12%~16.34%DM、39.60%~46.61%DM、19.49%~24.26%DM、1.67%~1.94%、206.09~262.64;除第一季燕麦粗蛋白含量外,各评价指标在不同品种间存在显著差异(P<0.05),其中第一季中品种太阳神的株高、NDF及ADF含量均高于其他品种,但其RFQ低于其他品种,而品种领袖的干草产量最大且K含量最低;第二季中品种青引1号的株高和干草产量均位列第一,其NDF、ADF含量居最高,贝勒的CP含量高于其他品种,青燕1号的K含量低于其他品种;株高及干、鲜草产量与CP、K、RFQ呈显著(P<0.05)或极显著(P<0.01或P<0.001)负相关,与NDF、ADF呈极显著正相关(P<0.001)。灰色关联度分析结果表明,各指标中NDF和RFQ的权重系数位列前二位,为该地区燕麦生产性能评价的重要指标;最适宜在鄂尔多斯高原北部地区作为第一季春播生产和第二季复种的燕麦品种分别为领袖和青燕1号,第一季春播领袖+第二季复种青燕1号的种植模式可在该地区以及同类型区域作为主推模式推广种植。

Study on the Effects of Extreme Precipitation for Seven Growth Stages of Winter Wheat in Northern Weihe Loess Plateau, China

The research on the characteristic frequency of precipitation is a great significance for guiding regional agricultural planning, water conservancy project designs, and drought and flood control. Droughts and floods occurred in northern Weihe Loess Plateau, affecting growing and yield of winter wheat in the area. Based on the daily precipitation data of 29 meteorological stations from 1981 to 2012, this study is to address the analysis of three different frequencies of annual precipitation at 5%, 50%, and 95%, and to determine the amount of rainfall excess and water shortage during seven growth stages of winter wheat at 5%, 10%, and 20% frequencies, respectively. Pearson type III curve was selected for this study to analyze the distribution frequency of annual rainfall and rainfall amount following seven growth stages of winter wheat crop in 29 stations of Northern Weihe loess plateau. As a result of our study, annual precipitation is gradually increasing from southwest to northeast of Northern Weihe loess plateau. The highest amount of annual precipitation occurred in the Baoji area and the lowest precipitation covered by the northwest area of Northern Weihe loess plateau. Moreover, the amount of rainfall of seven growth stages indicates that excessive rainfall occurs not only in the first stage (sowing to tillering) and seventh stage (flowering to ripening) but also in second stage (tillering to wintering). In the seventh stage, a large amount of excessive rainfall occurred in Changwu, Bin, Qianyang, Fengxiang, Baojiqu, and Baojixian. Moreover, water shortage is distributed in the third stage (from wintering to greening), the fourth stage (from greening to jointing), the fifth stage (from jointing to heading), and the sixth stage (from heading to flowering). Furthermore, the worst water shortages occurred in Hancheng, Heyang, Chengcheng, Pucheng, Dali, Tongchuan, and Fuping in the fourth stage (greening to jointing stage). Even though we study the crop water requirement under extreme rainfall conditions, the amount of rainwater still supply inadequate in some parts of the winter wheat growth stage. Therefore, this study provides main clues for the next step to study the irrigation water needs of winter wheat crops and to reduce agricultural risks in 29 counties in the northern loess plateau and other regions.

2001-2020年黄土高原植被生长季干旱的时空分布

基于MODIS实际蒸散量(ET)和潜在蒸散量(PET)反演作物缺水指数(CWSI),研究黄土高原生长季干旱时空变化特征,并用CWSI和植被归一化指数(NDVI)进行偏相关分析以探究生长季内最干旱月份对NDVI的影响。结果表明:1)黄土高原生长季CWSI多年平均值为0.777,处于中度干旱状态,空间分布表现为东南部较轻,西北部较严重的特征,且高程在1200~1700 m区域内的干旱程度最高;2)2001-2020年多年生长季CWSI整体呈显著下降趋势,其中2001年干旱程度最高,2018年干旱程度最低;在整个生长季内,黄土高原在4月的干旱程度最高;8月的干旱程度最低。具体表现为:4-10月,干旱等级从重旱过渡到中旱和轻旱,又从轻旱演变成中旱;3)从植被类型角度分析,荒漠、草原的分布区域属于重旱;草甸、栽培植被、灌丛的分布区域属于中旱;针叶林、阔叶林的分布区域属于轻旱,且不同植被类型在植被生长季的CWSI均呈波动下降趋势。研究结果可为黄土高原地区的生态预警和旱灾预估提供科学依据。

陇东旱塬区复种马铃薯栽培模式筛选

为研究陇东旱塬区冬油菜收获后复种马铃薯不同栽培模式对其产量及经济效益的影响,采用单因素试验区组设计,以陇薯7号原种马铃薯品种为试验材料,共设计8种栽培模式。通过对不同模式下马铃薯农艺性状、商品率、产量及经济效益的比较,筛选出最佳的冬油菜茬复种马铃薯栽培模式。结果表明,秸秆带状覆盖、平作起垄、垄沟种植3个栽培模式表现较好,667 m^(2)产量分别为2292.81、1917.63、1655.46 kg,比对照露地平作分别增产41.27%、18.15%和2.00%。

不同高寒草地生态区种植模式对饲草产量和营养品质的影响

研究燕麦(Avena sativa)分别与饲用豌豆(Pisum sativum)、箭筈豌豆(Vicia sativa)、蚕豆(V.faba)混播及4种作物单播在高寒不同生态区的生产性能,探讨适宜各生态区的最佳种植模式,为高寒不同生态区一年生混播草地的栽培提供依据。结果表明:1)各混播组合间,燕麦+饲用豌豆组合的干草产量和粗蛋白含量最高,分别为10.56 t·hm^(−2)和16.15%;3种混播组合的粗蛋白含量、可溶性糖含量、粗脂肪含量、中性洗涤纤维含量均介于燕麦单播和饲用豌豆、箭筈豌豆、蚕豆单播之间。2)各生态区间,燕麦和3种豆类的平均株高均随海拔高度的上升呈先增加后降低的趋势;门源的干草产量最高,为9.78 t·hm^(−2);除贵南外,粗蛋白含量亦随海拔高度的升高呈降低趋势,贵南的粗蛋白含量最高,为17.69%。3)综合评价得出,适宜各生态区种植的混播组合分别是祁连山流域门源和湟水谷地湟中的燕麦+饲用豌豆组合、三江源区贵南的燕麦+蚕豆组合、环青海湖区共和的燕麦+箭筈豌豆组合,干草产量分别为13.00和10.63、10.59、10.73 t·hm^(−2),粗蛋白含量分别为14.65%和16.11%、13.56%、12.01%;各生态区最佳混播组合的干草产量较燕麦单播分别增加了48.57%(门源)、23.17%(湟中)、23.00%(贵南)、47.80%(共和)。

豫西黄土高原果园生草对土壤线虫群落及结构的影响

土壤线虫是土壤生物中最丰富的后生动物,从线虫群落结构角度评价果园不同覆盖作物的土壤质量可为果园管理提供依据。2022年在黄土高原东部果园开展实验,供试品种为‘富士’苹果(Malus domestica cv. Fuji),处理包括:农田、单播毛苕子(Vicia sativa L.)、单播黑麦草(Lolium perenne L.)。与农田对照相比,覆盖毛苕子线虫总丰度及食细菌线虫相对丰度分别显著提高了302.33%和38.41%,植物寄生线虫与杂食和捕食线虫的相对丰度分别降低了62.18%和86.12%。覆盖黑麦草较对照处理导致杂食和捕食线虫的相对丰度降低了55.59%。土壤微生物碳含量、变形菌门相对丰度、土壤pH值、豆科生物量比例是影响线虫群落结构的主要因子。果园行间覆盖毛苕子可优化线虫群落结构,有利于果树根系的生长,建议豫西黄土高原果园生草选择豆科物种毛苕子为益。

黄土高原典型地区种植模式产量效应模拟与效益评价研究

利用作物生长模型软件包DSSAT3 ,模拟研究了黄土高原典型地区主要种植模式的产量效应与年际变异情况 ,并采用耗水系数、耗氮系数和经济收益值 ,综合评价了各种植模式的资源利用效率与经济效益 ,选择出了关中平原区、渭北高原区资源利用效益高、经济效益好的最优种植模式 ,分别为冬小麦 夏玉米、春玉米。

黄土高原小杂粮作物生产态势与地域分异

分不同地区和作物,对黄土高原小杂粮生产情况进行了系统研究,表明小杂粮在黄土高原旱作农区粮食生产中居重要地位。山西省小杂粮播种面积最大,甘肃省次之,宁夏回族自治区播种面积虽不及陕西省,但所占粮食播种面积的比重却较高。在不同小杂粮作物中,以马铃薯分布面积最大,谷子次之,其后依次是荞麦、绿豆,其他作物则分布相对较少。同时对小杂粮分布最为集中的黄土高原水土流失区主要小杂粮作物区域分布进行了研究,将该区分为3个区,10个亚区,评述了各区主要小杂粮生产和分布特点,为合理开发小杂粮资源提供决策依据。

高原地区农作物水热指标与特点的研究进展

通过对作物农业气象条件鉴定、作物农业气象试验研究、作物生态气候适应性分析和作物农业气候区划以及农业气象灾害调查记载对比评估分析等手段,整理和总结了髙原地区7种粮食作物、6种经济作物、6种特色作物、7种瓜果作物和4种中药材等共计30种农作物水热指标以及冬小麦和春小麦土壤水分指标.高原地区作物水热指标具有4个明显特点,釆用不同积温界限值来确定不同作物属性热量指标,喜凉、中性、喜温和喜热作物分別釆用≥0℃、≥5℃、≥10℃和≥15℃积温界限值作热量指标.不同温度带作物适宜的热量指标差异明显,有随温度带愈冷凉作物热量指标呈偏低的趋势.不同水分气候区作物水分指标差异较大,有随湿润度增加作物水分指标呈递减的趋势.作物水热指标随气候变化而发生缓慢变化,气候变暖使作物全生长期延长,对同一熟性品种而言,需要热量指标比变暖前有提高趋势;气候变干使作物水分指标有增加趋势.农作物水热指标是衡量作物适生种植的重要标准,是引种、作物布局、栽培管理、髙产优质安全生产的重要科学依据,是气象为农业服务必不可少的基础资料,也是服务工作的前提.

黄土旱塬不同施肥水平下小麦玉米轮作的产量与土壤水分效应模拟研究

在模拟精度验证基础上，应用WinEPIC模型模拟研究了黄土高原早塬地1957～1998年期间不同施肥水平下小麦玉米轮作方式“春玉米→春玉米→冬小麦→冬小麦→冬小麦→冬小麦”的产量变化和土壤水分效应。模拟结果表明：1）无肥、低肥、中肥和高肥处理下，小麦玉米轮作方式的模拟产量均呈现波动性降低趋势，其平均值分别为1．573、3．272、3．877和4．318t／hm^2，其适宜的施肥量范围为N90～120kg／hm^2、P30～60kg／hm^2；2）4种施肥处理下，小麦玉米轮作田逐月土壤有效含水量均呈现波动性降低趋势，平均每年分别减少8．5、10．3、12．3和12．0mm，无肥、低肥和中肥处理间土壤有效含水量差异十分显著；3）在模拟初期（1957～1962）出现了土壤湿度逐年降低、土壤干层逐年加厚的干燥化过程，在模拟中后期（1975～1980，1993～1998）均出现了稳定的土壤干层，无肥和低肥处理土壤干层分布于2—3m和2—4m土层，中肥和高肥处理均分布于2—5m土层，表现出随肥力和作物产量水平的提高，土壤干层厚度逐渐加深。

黄土高原区草粮(油)翻耕轮作的土壤水分及作物产量效应

为了评价苜蓿翻耕后进行不同轮作模式的水分适应性和经济效益,提出黄土高原区生态效益和经济效应较好的草田轮作模式。该文测定了6a生苜蓿草地翻耕后轮作农田和休闲地的土壤水分及作物产量,并进行经济效益分析。结果表明,不同草田轮作模式的土壤水分恢复作用存在差异。苜蓿地轮作第2年收获后,以苜蓿-休闲-休闲模式土壤水分状况最好,0～300cm土层土壤水分已接近连作农田水平,且100～340cm土层土壤水分较耕前出现了恢复现象;而苜蓿-冬小麦-冬小麦模式最差,土壤水分恢复层出现在120～320cm土层;6a生苜蓿地翻耕后经过2a轮作,0～500cm土层土壤水分仍未达到连作农田水平。轮作2a冬油菜平均籽粒产量和平均籽粒水分利用效率较连作冬油菜分别增加了34.9%、44.4%(P<0.05),轮作2a冬小麦平均籽粒产量和平均籽粒水分利用效率较连作冬小麦分别提高了45.0%、42.9%(P<0.05);效益分析表明,轮作2a冬小麦的平均产投比是连作2a冬小麦的近1.5倍,是轮作2a冬油菜的2.5倍,是连作2a冬油菜的3.4倍,6a生苜蓿地翻耕后轮作冬小麦比轮作冬油菜具有更高经济效益。该研究结果为黄土高原苜蓿草地可持续利用,建立稳定的旱地农业生态系统提供了理论依据。

中国黄土高原地区4～10月雨量时空变化特征分析

利用黄土高原区域40年的实测降水资料，研究了该区作物生长期（4～10月）降水量的时空变化特征，并对于年和湿年的降水进行了分析和比较。结果表明：黄土高原作物生长期降水在1985年左右发生突变，由历史上的多雨转为少雨；降水异常变化存在3～5年、8年左右和11～16年左右的振荡周期，3～5年的振荡周期更明显；干湿年降水存在明显差异，湿年比干年多40％以上；存在降水异常响应的敏感区，干旱在高原的东北部响应变幅大于其它地方，湿涝响应在高原的北部最为明显。

青海省近45年霜冻变化特征及其对主要作物的影响

利用青海省22个地面气象站1961-2005年霜冻气候资料及日最低气温资料，对东部农业区、柴达木盆地等地的霜冻气候变化特征以及对主要作物的影响进行研究。结果表明：45年来，青海省大部分地区早（秋）霜冻初日推迟，晚（春）霜冻终日提前，无霜冻期延长。东部农业区霜冻初日推迟、终日提前的趋势最为明显，柴达木盆地次之，祁连山地区和青南高原霜冻初日推迟趋势较明显，而终日提前趋势不明显；大部分地区重霜冻频数减少，强度减弱，春霜冻期低温强度变化趋势较秋霜冻期明显；气候变暖使早霜冻危害减轻，晚霜冻危害加重。

晋西黄土区果农间作土壤养分空间分布

为了研究黄土区农林复合系统土壤养分的空间分布及效应,对山西吉县残塬面核桃×花生、核桃×大豆和核桃×玉米3种典型果农间作类型下0～100cm土层中土壤有机质、全氮、速效磷和速效钾进行了测定和分析。结果表明:1)3种间作类型土壤养分的空间分布特征具有一定的相似性。在垂直方向上,土壤养分含量随土层深度的增加而减少,并且距果树越远,土壤养分的垂直递减梯度越小;在水平方向上,离果树越近,土壤养分越少。2)效应分析结果表明,间作系统中果树与作物存在竞争,间作系统中作物土壤养分的综合效应优劣说明间作作物以花生为最佳、大豆其次、玉米最差。根据研究结果提出了研究区果农间作系统减少土壤养分竞争的相关建议:加强水肥管理、增加果树和作物的间作距离、设置根障。

黄土高原地区耕作制度区划探讨

黄土高原地区气候类型多样、地貌特征复杂、水土流失严重,造成农业生产条件在区域上存在很大差异,因此,有必要对耕作制度进行分区,以指导该区农业生产发展。以热量(≥0℃积温)、水分(降水量、干燥度)、地貌等作为分区指标,以县(区)为基本单元,采用地理位置-地貌-水旱作-熟制的命名方法,将该区划分为10个耕作区,并描述了各区的自然与社会条件、作物类型、主要耕作方式及发展方向等。

黄土区农田作物降水利用效率影响因素及提高途径分析

降水资源高效转化利用对于提高旱地农业和灌溉农业生产综合效益均具有重要意义。通过对黄土区农田作物降水利用效率的概念及其影响因素、农田降水生产潜力等相关研究成果的分析,从实现土壤水库扩蓄增容、增加农田地面覆盖、促进作物根系生长、减少作物无效蒸腾、持续增加土壤肥力等5个方面,提出了提高黄土区农田降水利用效率的方法和途径,并结合降水资源转化利用技术发展需求,提出了近中期提高降水资源利用效率技术的发展方向和研发的若干重点。