中国陕西省施有机肥黄土NH4+固定的热力学性质

Some thermodynamic properties of NH₄⁺ fixation by loess soil in plowing and clay layers are discussed. The results indicate that the four ion adsorption equations commonly used can describe the properties of NH₄⁺ fixation in these soils under constant temperature. Among the four adsorption equations, the single-surface Langmuir equation is the best. When the concentration of NH₄Cl solution is 10^-1 mol below, the Freundlich equation can be used. The changes of apparent standard free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) illustrate that NH₄⁺ fixation in soil is an endothermic adsorption and spontaneous reaction, and the process can be enhanced by a higher temperature and clay content in soil. The "proper value of NH₄⁺ fixation by soil (K₁ × q_m) increased with increasing clay content and temperature. The heat of NH₄⁺ fixation in soil (Q_m) confirms the conclusions made in this paper.     

生物质炭对土壤N2O消耗的影响及其微生物影响机理

生物质炭在温室气体减排方面具有很大的发展前景,它不仅能实现固碳,对于在大气中停留时间长且增温潜势大的N₂O也能发挥积极作用。本研究采用室内厌氧培养试验,按照生物质炭与土壤质量比（0、1%和5%）加入一定量生物质炭,土壤重量含水率控制在20%。利用Robotized Incubation平台实时检测N₂O和N₂浓度变化,通过测定土壤中反硝化功能基因丰度（nirK、nirS、nosZ）分析生物质炭对N₂O消耗的影响及其微生物方面的影响机理。结果表明：经过20 h厌氧培养后,0生物质炭处理的反硝化功能基因丰度（基因拷贝数·g^-1）分别为6.80×10⁷（nirK）、5.59×10⁸（nirS）和1.22×10⁸（nosZ）。与0生物质炭处理相比,1%生物质炭处理的nirS基因丰度由最初的2.65×10⁸基因拷贝数·g^-1升至7.43×10⁸基因拷贝数·g^-1,nosZ基因丰度则提高了一个数量级,由4.82×10⁷基因拷贝数·g^-1升至1.50×10⁸基因拷贝数·g^-1,然而nirK基因丰度并无明显变化;5%生物质炭处理的反硝化功能基因丰度并未发生显著变化。试验结束时,添加生物质炭处理的N₂/（N₂O+N₂）比值也明显高于0生物质炭处理。相关性分析结果表明,nirS基因丰度和nosZ基因丰度均与N₂O浓度在0.01水平上显著相关。试验末期nirS基因丰度和nosZ基因丰度均随着N₂O浓度的降低而升高。因此在本试验中,添加1%生物质炭可显著提高nirS和nosZ基因型反硝化细菌的丰度,增大N₂/（N₂O+N₂）比值,促进N₂O彻底还原成N₂。生物质炭对于N₂O主要影响机理是增大了可以还原氧化亚氮的细菌活性,促进完全反硝化。     

土壤对磷的吸持特性及其与土壤供磷指标之间的关系

本试验测定了浙江省几种代表性土壤对磷的等温吸持特性。实测值与Frundlich、Langmuir、两项式Langmuir和Temkin方程都很符合,相关系数变化范围在0.919-0.999之间,都达到极显著水平。其中以简单Langmuir等温式与本实验资料最为吻合。从Langmuir方程得到的土壤吸持特性值(k×q_m)被认为与土壤供磷特性有关。几种供试样品的(k×q_m)值是:针铁矿21100>黄筋泥4218>黄筋泥田991>青紫泥798>粉泥田660>高岭石485>老黄筋泥田423>泥质田298。根据土壤吸持特性值以田菁进行盆栽试验来估算作物磷肥需要量,结果表明,供磷强度0.3ppm P基本能满足田菁早期生长的需要。为使不同土壤达到相同的供磷强度,(k×q_m)值大的土壤要求更高的有效磷值。供试土壤的几种磷素指标:E值、Bray1-P值和(NaOH-Na₂C₂O₄)法值对(k×q_m)值的变化比较敏感,而EDTA-P和Olsen-P指标对(k×q_m)值的变化较为迟钝。     

安徽省沿江地区双季稻光热资源利用效率变化特征及对气象产量的影响

为进一步了解安徽省沿江地区双季稻光温资源利用效率的变化特征及光温资源变化对双季稻气象产量的影响,以安徽省沿江地区19个市县气象观测站1961—2017年逐日日平均气温、日照时数及7个双季稻主产市县1961—2006年早稻和晚稻产量为基础,采用线性趋势、M-K突变检验、相关分析、回归分析等方法,分析了早稻、晚稻、双季稻生长季光热资源和利用效率变化特征及光热资源变化对气象产量的影响。结果表明,1961—2017年安徽省沿江地区早稻、晚稻和双季稻生长季太阳总辐射呈极显著下降趋势（P<0.01）,平均每10 a降幅分别为30.5 MJ·m^-2、69.8 MJ·m^-2和86.6 MJ·m^-2;≥10℃积温呈显著增加趋势,平均每10 a增幅分别为39.1℃·d、24.4℃·d和14.7℃·d。早稻、晚稻、双季稻光能和热量利用效率均呈显著增加趋势（P<0.01）,其中光能利用效率增幅分别为0.040%·（10a）^-1、0.103%·（10a）^-1和0.083%·（10a）^-1,热量利用效率平均每10 a增幅分别为0.141 kg·℃^-1·d^-1·hm^-2、0.39 kg·℃^-1·d^-1·hm^-2和0.315 kg·℃^-1·d^-1·hm^-2;早稻、晚稻和双季稻光热资源利用效率显著增加主要源于其产量的大幅提升。太阳总辐射、≥10℃积温与早稻气象产量分别呈极显著（P<0.01）、显著（P<0.05）正相关;晚稻气象产量与太阳总辐射呈显著（P<0.05）正相关,但与≥10℃积温相关性不显著（P>0.05）。太阳总辐射是影响早稻和晚稻气象产量的主要因子,≥10℃积温为次要因子;光热资源变化对早稻气象产量的影响较晚稻更为明显。在太阳总辐射减少、≥10℃积温增加趋势下,可通过选择光合效率高的品种,并采用薄膜育秧或温室育秧方式,增加早稻生长季积温,适当延长晚稻生育期等途径,提高安徽省沿江地区双季稻光热资源利用效率,实现水稻周年产量的高产稳产。     

CO2浓度升高条件下不同程度豌豆蚜危害对紫花苜蓿叶片营养物质和次生代谢物质的影响

由于人类大量开采使用石油、煤炭、天然气等化石燃料,使大气CO₂浓度升高,这不但加速全球变暖,还将影响地球上动植物的生存和分布,从而对整个生态系统产生深远影响。为探明CO₂浓度升高与豌豆蚜（Acyrthosiphon pisum）虫口密度对紫花苜蓿（Medicago sativa）叶片内化学物质的影响,明确CO₂浓度升高和蚜虫密度在紫花苜蓿生理生化中的作用,试验在CO₂光照培养箱内设置380 μL·L^-1（对照）、550 μL·L^-1和750 μL·L^-1 3个CO₂浓度培育苜蓿幼苗并接入10日龄成蚜10头·株^-1、20头·株^-1、30头·株^-1,并以0头·株^-1作为空白对照,1周后测定植物体内营养物质和次生代谢物质含量。结果表明,随CO₂浓度升高,蚜虫密度为30头·株^-1时紫花苜蓿可溶性蛋白、可溶性糖以及淀粉含量均上升,在750 μL·L^-1 CO₂浓度下分别比CK上升11.62倍、0.49倍和0.24倍;黄酮、总酚和简单酚含量也显著上升。随蚜虫危害程度加重,同一CO₂浓度下紫花苜蓿淀粉、简单酚含量先上升后下降,高CO₂浓度蚜虫密度为30头·株^-1时比0头·株^-1时可溶性糖、总酚以及单宁含量上升1.66倍、1.49 mg·g^-1和1.09 mg·g^-1,差异均显著（P<0.05）。说明具有固氮作用的豆科植物更易于适应CO₂浓度升高的变化,从而在受到刺吸胁迫后增强自身诱导抗虫性以抵御害虫为害。     

不同液土比和温度条件下塿土铵离子吸附

Effects of NH₄⁺ concentration, solution/soil ratio and temperature on NH₄⁺ adsorption were studied in a Eum-Orthic Anthrosol. The slopes of the soil NH₄⁺ adsorption isotherms and the fitted n, the coefficient for the adsorption intensity, and k, the coefficient related to adsorption capacity, of the Freundlich equation increased with increasing solution/soil ratio (SSR) and with decreasing temperature (T). For the range of experimental conditions, the value of ∂q/∂c, the rate of change of the amount of NH₄⁺ adsorbed in the soil solid phase (q) with respect to the equilibrium concentration of NH₄⁺ in soil solution (c), was 0.840, indicating that q increased with increasing c. From 2 to 45 ℃, ∂q/∂SSR, the rate of change of q with respect to SSR, decreased from 2.598 to 1.996, showing that q increased with increasing SSR, while its increasing rate decreased with temperature. From SSR 1:1 to 20:1, ∂q/∂T, the rate of change of q with respect to T, decreased from -0.095 to -0.361, indicating that q decreased with increasing temperature, and at the same time the negative effect of temperature became larger as SSR increased. Thus under the experimental conditions the order of importance in determining the amount of NH₄⁺ adsorbed in the soil solid phase was ∂q/∂SSR > ∂q/∂c > |∂q/∂T|, indicating that the greatest effect on the amount of NH₄⁺ adsorbed was with the solution/soil ratio; the equilibrium concentration of NH₄⁺ had a lesser effect; and temperature had the least effect.     

北京山区典型植被类型土壤饱和导水率及其影响因素

研究典型植被类型的土壤饱和导水率(K_s)分布及其影响因素,可为北京山区植被建设提供有力借鉴,同时加深对于土壤水分运动的理解。选取北京山区最具代表性的4种植被类型,获取不同类型、不同层次的土壤饱和导水率,调查土壤理化性质与根系生物量、石砾体积,利用Pearson相关性分析、多元逐步回归、通径分析,明晰了北京山区典型植被类型下的土壤饱和导水率分布及其影响因素。结果表明:(1)土壤饱和导水率介于0.05~2.23 mm/min,属于高度变异,随土层向下不断减小,侧柏×灌木混交林、侧柏纯林与侧柏×五角枫混交林的土壤饱和导水率存在显著差异(p＜0.05)。土壤饱和导水率与土层深度之间的关系符合对数函数关系式y=±aln x+b,R²≥0.858。(2)相关性分析结果表明,土壤饱和导水率与容重、总孔隙度、毛管孔隙度、根系生物量、有机质含量均呈极显著相关关系(p＜0.01),与非毛管孔隙度、自然含水率呈显著相关关系(p＜0.05)。(3)逐步回归分析得Y=3.42X₂+0.78X₆-1.333,R²=0.862。进一步通径分析可知,根系生物量主要通过直接作用影响土壤饱和导水率,而总孔隙度通过间接作用影响土壤饱和导水率。可知,侧柏×灌木混交林的导水性能最佳,后续的植被建设应重点考虑侧柏×灌木混交林,以达到减少径流、涵养水源的目的。     

盐胁迫下硝态氮对囊果碱蓬根系发育和氮吸收的影响

The effiects of NaCl salinity and NO₃^- on growth, root morphology, and nitrogen uptake of a halophyte Suaeda physophora were evaluated in a factorial experiment with four concentrations of NaCl (1, 150, 300, and 450 mmol L^-1) and three NO₃^- levels (0.05, 5, and 10 mmol L^-1) in solution culture for 30 d. Addition of NO₃^- at 10 mmol L^-1 significantly improved the shoot (P < 0.001) and root (P < 0.001) growth and the promotive effect of NO₃^- was more pronounced on root dry weight despite the high NaCl concentration in the culture solution, leading to a significant increase in the root:shoot ratio (P < 0.01). Lateral root length, but not primary root length, considerably increased with increasing NaCl salinity and NO₃^- levels (P < 0.001), implying that Na⁺ and NO₃^- in the culture solution simultaneously stimulated lateral root growth. Concentrations of Na⁺ in plant tissues were also significantly increased by higher NaCl treatments (P < 0.001). At 10 mmol L^-1 NO₃^- , the concentrations of NO₃^- and total nitrogen and nitrate reductase activities in the roots were remarkably reduced by increasing salinity (P < 0.001), but were unaffected in the shoots. The results indicated that the fine lateral root development and effective nitrogen uptake of the shoots might contribute to high salt tolerance of S. physophora under adequate NO₃^- supply.     

区域性土壤流失预测方程的初步研究

应用我国南方花岗岩侵蚀红壤区的径流小区观测资料,采用数值分析方法推导出适合花岗岩侵蚀红壤区,计算各次降雨吋土壤流失量和年土壤流失量方程:A₁=4·y_s·K·LS;并利用野外调查量测资料,推导出适合长江三峡低中山区的土壤流失方程:A₂=(152.5D-1016)·R·LS·C^-2.3利用上述方程可以预测特定区域的土壤流失量。     

华中地区旱地氮素矿化的能力

Nitrogen mineralization potentials of 15 soil samples were studied by the methods of soil aerobic incubation, and the correlation between the potentials and the amounts of nitrogen taken up by rye grass (Lolium multiflorum Lam.) in pot culture was calculated. The soils were collected from Hubei Province in Central China. Soil nitrogen mineralization potentials (N_O) were calculated and optimized by a quick-BASIC program. N_O ranged from 60 mg kg^-1 to 340 mg kg^-1, which accounted for 9.1% to 34.6% of the total nitrogen content. Among the examined soils, yellow-brown soil collected from Wuhan had the largest N_O and brown-red soil from Xianning had the smallest one. The mineralization rate constants (k) ranged from 0.00556 d^-1 to 0.01280 d^-1, in average 0.00882 d^-1. Chao soil from Wuhan had the greatest k while yellow-cinnamon soil from Zhaoyang had the smallest one. There were apparent differences between mineralization parameters (N_O and k) optimized and non-optimized ones. Optimized N_O had a better correlation than non-optimized N_O with the amount of nitrogen accumulated in the aerial parts of rye grass. N_O, N_O × k and N_t(accumulated mineralized nitrogen within time t) could be used as indexes of soil nitrogen supply. Among them N_t was the best, which was significantly correlated with the amounts of nitrogen accumulated in the aerial parts of rye grass harvested at three different times.