外源胡敏酸对土壤有机质组分变化的影响及其与茶树铅有效性的关系

盆栽试验分析了胡敏酸输入土壤6个月后茶树根际和非根际土壤有机质SOM及其组分,包括水溶性物质WSS、富啡酸FA、胡敏酸HA以及土壤微生物生物量SMB的变化,并对不同土壤有机质组分碳含量和茶树不同组织铅含量作了相关性分析。外源胡敏酸设置3个浓度水平（0、300、600 mg kg-1）,铅设置2个浓度水平（0、300 mg kg-1）,试验共有6个处理。茶苗置于温室培养,6个月后分新叶、老叶、新茎、老茎、根收获。结果表明：根际并非总是富含有机质,未加铅处理根际SOM含量低于非根际;而加铅处理根际SOM含量高于非根际。HA加入土壤能够显著增加根际和非根际SOM和SMB的含量,但是加铅处理和不加铅处理增加幅度不同。高浓度HA显著增加了根际FA的含量,可能是HA部分裂解所致。非根际有机质各组分与茶树铅含量无显著相关关系;根际SOM、HA和茶树不同组织铅含量没有显著相关关系。根际WSS、FA与茶树嫩叶、老叶、嫩茎、老茎以及根部铅含量均存在显著或极显著正相关关系;而根际SMB与茶树各个组织铅含量存在显著负相关关系。总之,胡敏酸施入土壤改变了土壤有机质及其各个组分的含量,而根际某些土壤有机质组分的改变又显著影响了茶树不同组织铅的吸收和分布。     

Nitrogen applications modify seed and oil yields and fatty acid composition of winter mustard

Winter mustard (Brassica juncea L.) is not a common crop in the Southeastern United States. With increased interest in biodiesel production, there has been corresponding interest in mustard in this region. The objective of this study was to evaluate the effect of N fertilization (0, 50, 100, 150 kg N ha⁻¹) on productivity, oil content, and oil composition of winter mustard ‘Pacific Gold’ grown at three locations in Mississippi (Stoneville, and two locations at Verona, namely Verona silt loam (Verona-SL) and Verona clay (Verona-C)). Nitrogen did not affect oil content (percent oil). Seed and oil yields (kg ha⁻¹) increased with N application relative to the unfertilized control. At the Verona-C location, the concentration of oleic acid was higher in the 50 kg N ha⁻¹ treatment. At Stoneville, linolenic acid concentration was higher in the 150 kg N ha⁻¹ and lower in the 100 kg/N ha⁻¹ treatment, while it was not different in the other treatments. Overall, the yield of the fatty acids (FA) palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, eicosanoic, behenic, erucic, lignoceric, and nervonic acid increased with higher N rates (100 or 150 kg N/h). The highest yield of FA in the two Verona locations were achieved in the 100 kg N ha⁻¹, while greatest yield of FA at Stoneville was achieved in the highest N rate (150 kg N ha⁻¹). Means of mustard oil yields in our study in the higher fertility treatment ranged from 737 to 1094 kg ha⁻¹. This study demonstrated winter mustard production in Mississippi and possibly other areas in the Southeastern United States can be successful and could provide seed and oil yields comparable to yields from other production areas.     

Oil productivity and composition of sunflower as a function of hybrid and planting date

Sunflower (Helianthus annuus L.) is a potential cash crop for the southeastern United States for production of cooking oil or biodiesel. Two years (2006 and 2007) of experiments were conducted at each of five locations in Mississippi to evaluate the effect of planting date (April 20, May 20, and June 20), and hybrid (DKF3875, DKF2990, DKF3510, DKF3901, PR63M80, PR62A91, PR63A21, PR63M91, and PR64H41) on seed yield, oil content, and oil composition of sunflower. Seed oil concentration varied from 25 to 47%. The oleic acid concentration in the oil was greater than 85% for DKF3510 and PR64H41, above 65% for PR63M80 and PR63M91, and intermediate for the other hybrids. Total saturated fatty acids (TSFA) concentration in the oil (the sum of palmitic, stearic, arachidic, behenic, and lignoceric acids) ranged from 6.3 to 13.0%, with DKF3510, PR63M91, and PR64H41 having lower concentration of TSFA than the other hybrids. Mean seed yields ranged from 997 to 2096 kg ha⁻¹ depending on location. Mean oil yields at the five locations ranged from 380 to 687 kg ha⁻¹, and calculated biodiesel production ranged from 304 to 550 kg ha⁻¹. Seed and oil yields in this study suggest sunflower in Mississippi should be planted by the last week of May. Later planting (20 June) may significantly decrease both seed and oil yields in the non-irrigated system in Mississippi and in other areas of the southeastern United States with similar environmental conditions.     

杉木林取代杂木林后土壤腐殖质组成及特性变化的研究

本文通过对南平溪后安曹下杉木丰产林（７０年）和山脊上保留的杂木林土壤腐殖质组成（ＨＡ和ＦＡ）、胡敏酸光密度值、腐殖质不同结合形态比较分析结果表明：杉木林取代杂木林后土壤有机质和腐殖酸类含量下降，ＨＡ／ＦＡ和Ｅ４值降低，Ｅ４／Ｅ６值增大，土壤中松结合态（Ⅰ）和紧结合态（Ⅲ）腐殖质减少，土壤腐殖质质量下降趋势较为明显．这可能亦是杉木林连栽土壤肥力退化的主要原因之一．     

FTIR‐spectroscopic characterization of humic acids and humin fractions obtained by advanced NaOH,Na4P2O7, and Na2CO3 extraction procedures

Aim of our study was the development of the methodological basis for the characterization of humic fractions of a long‐term field experiment. Humic acids (HAs) were extracted from three layers of a nontilled soil using three different extractants (1 M NaOH, 0.1 M Na₄P₂O₇, 1 M Na₂CO₃), and the humin fraction was enriched. NaOH as extractant for FTIR analysis of humic substances yields higher resolved IR spectra, especially in the important regions of stretching vibrations including aromatic and aliphatic groups and in the fingerprint area including amides, aliphats, and aromats than the other extractants. The NaOH extraction has lower extraction yields as compared to Na₄P₂O₇ and Na₂CO₃ and represents a different part of the soil organic matter (SOM). This is reflected by lower C : N ratios and higher E₄ : E₆ and fulvic acid–to–humic acid ratios as compared to the other extractants. The FTIR band areas of HA fraction obtained by NaOH showed an increase of the aromatic and carbonyl groups and a decrease of amide groups with increasing soil depth. Aliphatic groups showed contradicting results: The bands of the stretching vibrations increased, and the band of the bending vibrations decreased. We assume that band interactions in the bending vibrations were responsible for that phenomenon under the assumption of an increase of aliphatic groups with increasing soil depth. The IR bands of the enriched humin fraction showed a decreasing trend in case of both aliphatic bands deriving from stretching vibrations and an increase of aromatic characteristics with depth. Our study led to the conclusion that HA fractions obtained by 1 M NaOH represent a small and dynamic fraction indicated by the measured yields in combination with values of N_t, C : N, E₄ : E₆ ratios, and ratios of fulvic acids (FA) to HA. The humin fraction has a high contribution to the total organic C and represents a more stabilized fraction of SOM which still shows changes in its aromatic and aliphatic characteristics with soil depth.     

高黎贡山土壤腐殖质特性与团聚体数量特征研究

采用野外调查与室内分析结合的方法,研究高黎贡山土壤腐殖质特性与团聚体数量特征,对进一步了解高黎贡山生态系统中土壤特征,降低土壤侵蚀,减少水土流失提供科学依据。结果表明:土壤腐殖质的组成具有明显地带性特征,有机质、腐殖酸含量、胡/富(HA/FA)随海拔高度的降低呈先上升后下降的趋势,A1层胡敏酸(HA)、富里酸(FA)含量分布规律为暗棕壤棕壤棕色针叶林土亚高山草甸土黄棕壤黄壤黄红壤。A2层腐殖酸、FA变化趋势为暗棕壤棕壤棕色针叶林土黄棕壤黄壤亚高山草甸土黄红壤。A1层HA、FA分子复杂程度、化学稳定性比A2层强。1～0.5mm和0.25mm粒径的团聚体含量占绝大多数,约占60%～70%。随着海拔高度的降低,粗粒减少,细粒增多。土壤团聚体服从对数正态分布,其几何平均直径与几何标准差、土壤可蚀性K值之间存在负相关关系,土壤可蚀性K值与几何标准差存在正相关关系,同时土壤也具有一定的分形特性。其中亚高山草甸土几何平均直径(Dg)、平均重量直径(MWD)值最大,几何标准差(δg)、可蚀性K值、分形维数(CFD)值最小,土壤结构稳定性和抗蚀能力相对较强。胡敏酸含量是影响土壤可蚀性的重要因素。     

黄腐酸对作物根冠通讯影响的研究

通过室内圆柱管栽培,研究黄腐酸对春小麦根源信号和水分利用效率的影响。相对于WI处理,FA处理和DI处理从苗期到分蘖期叶片气孔导度显著下降,但叶水势基本不变,表明有非水根信号产生,其作用主要集中于苗期到分蘖期。与DI处理相比,FA处理受根源信号影响较小,其水分利用效率显著高于其他处理,这意味着黄腐酸可以通过调节根冠通讯来提高作物对水分的利用效率。     

FA旱地龙对旱地桑园的影响

旱地桑园用４００倍ＦＡ旱地龙稀稀液喷叶,有减国夏季秋桑树旱情,提高桑叶的产量。     

圆叶决明牧草料栽培金顶侧耳对其产量和品质及重金属含量的影响

以圆叶决明豆科牧草为主原料栽培金顶侧耳，研究了该原料对金顶侧耳的产量、品质及重金属含量的影响。结果表明，其子实体产量比棉子壳料栽培的对照处理提高23．98％，而且可以明显改良菇类的品质。其子实体中硬脂酸、棕榈酸和亚油酸含量分别比对照提高40．0％、10．1％和3．1％，金顶侧耳子实体的化学评分(CS)、营养指数(NI)和生物价(BV)等品质评价指数分别比对照处理(棉子壳料)提高10．7％、7．1％和12．7％，而且子实体中Cd、Pb、Cr重金属含量分别比对照下降5倍、1倍和0．5倍。以圆叶决明牧草为主原料栽培的金顶侧耳子实体饱和脂肪酸(SFA)、单不饱和脂肪酸(MUSFA)、多不饱和脂肪酸(PUSFA)均高于棉子壳栽培料的对照处理。圆叶决明牧草料栽培的子实体SFA：MUSFA：PUSFA=1：0．17：4．44，而棉子壳料栽培的子实体SFA：MUSFA：PUSFA=1：0．22：4．76，显示了一定的差异。以圆叶决明牧草料栽培的金顶侧耳子实体K、P、Cu、Zn、Fe、Mn的含量分别为2．80％、1．22％、26．90％、136．23％、135．13％、10．25％，而棉子壳料的对照处理则相应为3．16％、1．03％、29．93％、67．74％、69．71％和67．70％，两者之间呈现明显的差异。     

新疆南疆盐渍化棉田FA旱地龙施用效果及推荐施用量研究

新疆是中国重要的棉粮基地之一,但长期以来土壤盐碱化与次生盐碱化一直是制约农业发展的关键因素之一,如何改良盐碱地一直是研究热点。腐植酸型土壤改良剂FA旱地龙施入低肥力重盐渍化棉田,以改良土壤盐碱以及棉花长势及产量为评价指标,研究其对盐渍化土壤的改良效果,并探讨其合适的施用量。结果表明：（1）FA旱地龙起到蓄水保墒的作用,对FA旱地龙施用量和土壤保水性能做相关性分析表明,二者呈极显著的正相关关系;（2）能够有效降低盐碱,将0~60 cm深度土壤盐分控制在0.5 ms/cm左右;（3）随着改良剂施用量的增加,棉花株高、茎粗、棉花叶面积和产量均增加。最终从产量、脱盐效果、FA旱地龙投入成本及所获得的经济效益等方面综合分析,确定新疆南疆盐渍化棉田施用FA旱地龙改良剂1500~2950.5 kg/hm2之间,均能达到较为理想的保水抑盐以及增产增收的效果。