草地类型梯度分析

紫泥泉地区位于天山北坡低山带，具有代表性的冬春秋放牧场。本文应用数量分类（ＴＷＩＮＳＰＡＮ）、排序（ＤＣＡ）和回归分析方法研究了草地类型的分类及其分布的梯度规律。研究结果表明：该地区的草地类型按传统分类划分出１８个型，ＴＷＩＮＳＰＡＮ分类结合ＤＣＡ排序归纳出８个型，其中６个型为地带性草地类型，２个型为非地带性草池类型；地带性草地类型沿水热梯度分布，非地带性草地类型沿质地梯度分布。     

黔中黄壤丘陵旱坡地香根草、紫穗槐的水土保持效应

通过4年连续的定点、定位试验研究，结果表明：香根草、紫穗槐生物埂保水能力在第3年后达到或超过次生植被的保水能力；香根草生物埂第2年后保水能力超过紫穗槐生物埂，第3年后无土壤侵蚀发生；紫穗槐 生物埂第2年即无土壤侵蚀发生；香根草、紫穗槐生物埂降低土壤坡度的作用非常明显；种植香根草、紫穗槐生物埂后，玉米产量呈逐年增加的趋势。该技术适宜在黔中乃至全省推广种植。     

江西省主要人工混交林类型的优化与筛选

以杉木或湿地松为主要树种,用南酸枣、檫树、樟树、乐昌含笑、福建柏、鹅掌楸、蓝果树等作伴生树种,开展了13个类型的混交林试验研究,在定性分析筛选的基础上,初选出9个比较优良的混交类型,再依据Ii=P1h/H+P2d/D+P3v/V计算出混交类型的优选指标,用I标准=I单均+aδn计算出类型的优化标准为6.12.据此对参试的混交类型进行优选,选出的最佳混交类型为杉木+南酸枣、杉木+檫树、杉木+樟树和湿地松+鹅掌楸4个混交类型,供林业生产上推广应用.     

1QJ-120型浅松机的研究设计

针对旧式浅松机表土作业中秸秆和土壤侧向位移问题,分析和优化了浅松机的技术参数,设计了一种新型的1QJ-120型浅松机。该机适用于旱作保护性耕作播前作业,能够达到除草、整地和提高地温等目的,也可以用于中耕除草作业。     

测定石膏性盐渍土水溶性盐的适宜水土比

土壤水溶性盐的含量与组成随制备浸出液的水土比例不同而异,对含石膏的盐渍土测定结果的影响尤为显著。为了正确反映田间水溶性盐的实际状况,作者进行了三种不同水土比例制备浸出液的对比试验。结果表明,适宜水土比为1:1,其测出的盐分含量与饱和泥浆法按近,且操作简便、快速,在我国一般土化分析实验室均可采用。     

黄河中游水土保持措施保存率分析及措施状况评述──以黄河河龙区间南片为例

本文以土地详查、淤地坝普查成果为基本依据，结合典型调查，研究分析了河龙区间南片水土保持各项措施的保存率，认为在空间尺度上，分行政区给出的保存率较为真实的反映了社会环境、自然环境因素的相对作用程度及其主导关系，且有实际应用意义，据此文中进一步核实评述了该区水保措施的保存面积、措施结构及质量等。该区水保措施的状况在黄河中游干旱半干旱地区具有广泛的代表性，分析结果可作为水沙分析、水保规划、土地资源与环境评价等工作的重要参考依据。     

永丰草地的类型及其生产力评估

本文描述了甘肃省天祝县永丰草地的主要草地类型、生产能力及利用模式。研究工作显示,草地改良措施,对不同植被的生物量分布,将产生显著的效果。灌溉和施肥,将促进河谷草甸的地下生物量向地上生物量的转化过程。灌溉可使河谷草甸中禾草组分的增加超过50％,使产草量增加50％～100％。上年秋天和当年春天土壤的含水量,是全年产草量的决定因素,其对产草量的重要性超过全年平均降水量的影响。除了植被组分、产草量的变化外,河谷草地在可消化粗蛋白、可消化能、代谢能等方面也有重大变化,9月份与4月份相比,这三项指标分别高出376％、86％和86％。不同年龄组的绵羊饲料消耗显示,7岁羊的饲料消耗是10月龄羊的17倍;但是7岁羊的胴体重量仅是10月龄羊的2倍。根据永丰滩草地、饲草、家畜的这些特点,当地的畜牧业,不应当在毫无经济意义的情况下,保持太多的牲畜头数,优化畜产品生产的最好方法,就是实行季节畜牧业。季节畜牧业(其中繁殖母羊数达67％)与其他草地改良措施相结合,将使该地区单位面积上的绵羊的产肉量提高4.9倍。     

Compatible measurements of volumetric soil water content using a neutron probe and Diviner 2000 after field calibration

Field calibrations for a neutron probe and a capacitance sensor (Diviner 2000) for measuring the soil water content of a shrinking–swelling clay soil were substantially different from commonly used default values. Using our field calibrations, the two instruments estimated similar changes in the cumulative water content of a soil profile (0–1 m depth) over one growing season.     

新疆水土保持情况调查

新疆水土保持情况调查郭廷辅，佟伟力（水利部水土保持司，北京１００７６１）我们于１９９４年８月１１日至２６日对新疆伊犁、和田、喀什、吐鲁番、昌吉、乌鲁木齐等６个地区（州、市）的１１个县（市）、两个流域的水土流失情况和开展治理工作做了典型调查。同时，也对...     

In situ radiometric mapping of soil erosion and field-moist bulk density on cultivated fields

Abstract. Recent developments in in situγ ray spectrometry offer a new approach to measuring the activity of radionuclides such as ¹³⁷Cs and ⁴⁰K in soils, and thus estimating erosion or deposition rates and field moist bulk density (ρ_m). Such estimates would be rapid and involve minimal site disturbance, especially important where archaeological remains are present. This paper presents the results of a pilot investigation of an eroded field in Scotland in which a portable hyper pure germanium (HPGe) detector was used to measure γ ray spectra in situ. The gamma (γ) photon flux observed at the soil surface is a function of the ¹³⁷Cs inventory, its depth distribution characteristics and ρ_m. A coefficient, Q_Cs, derived from the forward scattering of ¹³⁷Cs γ ray photons within the soil profile relative to the ¹³⁷Cs full energy peak (662 keV), was used to correct the in situ calibration for changes in the ¹³⁷Cs vertical distribution in the ploughed field, a function of tillage, soil accumulation and ρ_m. Based on only 8 measurements, the agreement between in situγ ray spectrometry and soil sample measurements of ¹³⁷Cs inventories improved from a non significant r²=0.05 to a significant r²=0.62 (P<0.05). Erosion and deposition rates calculated from the corrected in situ¹³⁷Cs measurements had a similarly good agreement with those calculated from soil cores. Mean soil bulk density was also calculated using a separate coefficient, Q_K, derived from the forward scattering γ photons from ⁴⁰K within the soil relative to the ⁴⁰K full energy peak (1460 keV). Again there was good agreement with soil core measurements (r²=0.64; P<0.05). The precision of the in situ¹³⁷Cs measurement was limited by the precision with which Q_Cs can be estimated, a function of the low ¹³⁷Cs deposition levels associated with the weapons testing fallout and relatively low detector efficiency (35%). In contrast, the precision of the in situ ρ_m determination was only limited by the spatial variability associated with soil sampling.