模拟降雨条件下施磷量对褐土无机磷含量及形态转化的影响

采用室内土柱模拟试验,研究在山东平均降雨条件下不同施磷量对褐土各组分无机磷含量及形态转化的影响.结果表明,经过模拟降雨后,在0～10 cm土层中,各施磷处理的无机磷总量随着施磷量的增加而升高;随着土层的加深(10～50 cm),各土层无机磷总量是施磷量为P2(180 kg/hm2)时最高.而在10-30 cm土层,是施磷量为P3(1440 ks/hm2)的土壤无机磷总量高于P1,而在30～50 cm则是P1高于P3.同时,不同施磷量对磷组分含量及其占无机磷总量的比例都发生了改变,当施磷量分别为P1、P2和P3时,各无机磷组分的含量及所占比例按高低排序分别为:Ca10-P>Al-P,O-P>Ca8-P>Fe-P>Ca2-P;O-P>Ca8-P,Ca10-P>Fe-P,AI-P>Ca2-P和Ca10-P,O-P>Fe-P,Ca8-P>Al-P>Ca2-P.随着土层深度的加深,O-P、Fe-P和Ca10-P的含量保持相对稳定,而有效态无机磷源(Ca2-P、Ca8-P和AI-P)有降低的趋势;在小雨强度下,不同施磷量处理的土壤磷淋失量差异不显著,而随着降雨强度的加大,P3处理的土壤磷淋失量明显高于PI和P2处理的磷淋失量.以上结果说明,施磷量显著影响无机磷总量、各组分无机磷含量及其转化;在大于中等降雨条件下,高磷处理磷淋失量明显高于低磷处理磷淋失量.     

凤城市耕地土壤有机质时空变化研究

为掌握凤城市耕地土壤的肥力状况,对比分析近25 a的土壤有机质含量变化情况。结果表明:近25 a凤城市各乡镇(区)土壤有机质平均含量由较缺乏转化为中等水平;随着耕作年限的增加,较小比例的五级(缺乏)水平耕地消失。     

土壤含水量的Kriging和Cokriging估值研究

分析了田间同深度土壤含水量的半方差和不同深度土壤含水量的交互半方差特征 ,探讨了土壤含水量的Kriging和Cokriging估值方法。研究表明 ,同深度土壤含水量与不同深度的土壤含水量之间均具有显著的空间相关性 ,用Kriging方法进行土壤含水量的估值精度较传统方法高。加入浅层土壤含水量用Cokriging方法来估测深层土壤含水量 ,可进一步提高估值精度     

基于自然光照反射光谱的温室黄瓜叶片含氮量预测

利用便携式光谱辐射仪测量了自然光照条件下温室黄瓜叶片的光谱反射率,并计算了反射率光谱的一次微分光谱。反射率光谱以及一次微分光谱与叶片含氮量的相关分析表明,温室内光谱特性与叶片含氮量相关性最大的敏感波段分别是505～664 nm和685～722 nm。当利用原始光谱进行分析时,通过变量筛选得到了4个敏感波长,分别是568、596、640和664 nm。偏最小二乘回归分析(PLSR)以及归一化颜色指数(NDCI)分析都表明,建模时的相关系数R_C>0.800,模型验证时的相关系数R_V>0.700。对微分光谱进行的相关分析结果表明,利用单一敏感波长520 nm就可获得理想模型,建模时的相关系数为0.880,模型验证时的相关系数为0.787。对比原始光谱的PLSR模型与一阶微分光谱的一元线性回归模型可以得知,原始光谱以及一阶微分光谱都可用于温室内叶片含氮量的预测,而且一阶微分光谱在一些特殊的波长处具有更高的预测能力,这些模型将成为开发便携式作物长势诊断仪器的技术基础。     

In-field calibration of a dielectric soil moisture meter designed for use in an access tube

Abstract. The in-field calibration of a dielectric probe to measure soil water content is described. The probe uses an access tube analogous to that of the neutron probe. The dielectric constant was measured at soil depths of 10, 20, 30, 40, 60 and 100 cm. Cores of soil were then taken from the face of pits dug 30 cm from the access tube and their soil water contents determined by oven drying. The dielectric constant values measured by the probe were calibrated against water contents from these cores. We found that sensor depth needed to be included to achieve a good calibration model that explained 72% of the variance. It is argued that depth needs to be included because of artefacts introduced during the installation of the access tube.     

Evaluation of a combined penetrometer for simultaneous measurement of penetration resistance and soil water content

A combined penetrometer is an appropriate tool to measure the soil cone resistance and the water‐content profile. As a relatively new technique, a combined capacitance‐penetrometer for the simultaneous measurement of cone index and soil water content was developed at the Department of Agricultural Engineering of Bonn University in 2002. The objective of this study was the evaluation of the effectiveness and applicability of the innovated penetrometer with a focus on three aspects: (1) A capacitance sensor with two electrode configurations was calibrated for silt loam, sandy loam, and sand. The calibration results show that both electrode configurations have sufficient water‐content sensitivity, but soil‐specific calibrations seem necessary. (2) Under laboratory conditions, the dynamic resolution and response of the capacitance‐penetrometer were validated, and its radius of influence was determined. (3) The field measurement results demonstrate that this measurement technique can be used to improve the interpretation quality of soil cone index data.     

典型黑土pH值变化对营养元素有效态含量的影响研究

采用室内培养实验的方法,控制典型黑土样品的酸碱度值,探讨典型黑土中Cu、Zn、Mn、P和Fe等营养元素有效态含量与pH值的关系。结果表明:pH值变化0.5个单位左右,有效态铜含量变化约0.5～1倍;有效态锰含量变化约3～5倍;有效态锌含量变化9～15倍之多;有效态磷含量变化约1.5～2倍;有效态铁含量变化约3～4倍。说明精确掌握土壤的酸碱度值对于土壤诊断、合理施肥、提高作物产量和实现土地的可持续利用都具有重要的理论与实践意义。     

Genetics of nitrate content of lettuce, 1: Analysis of generation means

Summary The genetics of nitrate content in butterhead lettuce (Lactuca sativa L.) was studied using the mean values of five parental genotypes and several generations obtained from crosses between them. One high nitrate parental genotype was chosen and four low nitrate ones. A diallel analysis showed additive genetic effects to be the major source of variation in generation means. Estimates of additive genetic effects differed significantly between experiments, indicating genotype x experiment interactions. Effects of dominance were relatively small. The size and direction of dominance varied between experiments. Reciprocal differences were of very limited size and also varied between experiments. The inheritance of nitrate content in lettuce fitted the additive-dominance genetic model.     

储藏条件对水稻种子发芽活性影响的研究

文章讨论了储藏中水稻种子的水分含量、储藏温度和气体条件（如ＣＯ２气体、脱氧剂等）对水稻处子发芽活性的影响。     

“6?13”强冰雹天气雷达特征分析及对农业的影响

为了找寻冰雹天气发生的原因及对农业的影响,利用多普勒雷达的反射率因子、径向速度、垂直累积液态水含量(VIL)等产品,结合高低空环流形势及地面资料,对发生在长治市2016 年6 月13 日的强冰雹天气过程进行分析。结果表明：（1）此次冰雹天气是由高空冷槽和与地面暖低压共同作用结果;（2）强回波与三体散射(TBSS)对提前预报强冰雹有较好的指示意义;速度场的辐合辐散可以判断回波未来发展趋势,增强预判准确性;当TBSS出现一定的持续性时,TBSS可以作为强冰雹预警的辅助指标;VIL是判别冰雹的有效工具之一,且对冰雹的预报有较好的指示作用;（3）加强冰雹监测,通过及时的“点”监测,实现“面”预警,是减少冰雹对农业生产造成灾害的一种有效的补充手段。