沼渣对土壤酶活性的影响

通过在种植茄子0～100d内,不施有机肥（CK）与加入沼渣的对比试验中,研究土壤中有机质和土壤酶活性的变化情况。结果表明：施用沼渣的土壤总有机质呈上升趋势,比对照提高61.7%。不施有机肥的土壤（CK）活性有机质含量呈现下降趋势,当茄子生长到100d时,土壤活性有机质比初始降低了8.8%。施用沼渣的土壤中脲酶、转化酶和脱氢酶活性最高。相关性分析显示,脲酶、转化酶和脱氢酶活性与土壤有机质呈显著相关。用沼渣作有机肥能有效提高土壤有机质含量和土壤酶活性。     

沼渣与化肥配合施用对温室番茄生长发育、产量及品质的影响

采用随机区组试验设计,研究了沼渣与化肥配合施用对番茄生长发育、产量和品质的影响.结果表明:沼渣与化肥配合施用有利于番茄生长发育,其中60%沼渣+40%化肥处理的植株生长发育状况良好,产量高于其他处理;60%沼渣+40%化肥处理果实Vc含量为91.09 mg.kg-1,比对照高21.32 mg.kg-1,总糖含量比对照高2.13%,果实品质有明显改善.在试验组合中,60%沼渣与40%化肥配合施用为设施番茄的最佳配比.     

施用有机肥对棕壤和草甸土固钾作用的影响研究

通过室内恒湿和干湿交替培养试验,研究了沈阳地区耕地棕壤和草甸土的固钾特征,及其施用有机肥后对土壤固钾作用的影响。结果表明,在保持土壤处于田间持水量的恒湿条件下,两种土壤对外源钾都能够产生快速固定作用,经过1d培养土壤的固钾作用就可以达到平衡,但干湿交替培养可以提高土壤固钾量26．80％～33．27％;土壤施用有机肥后,在恒湿和干湿交替培养条件下均可以降低土壤的固钾强度,其中,施用有机肥6％处理的恒湿培养15d后,棕壤和草甸土的固钾量分别降低了25．71％和36．62％。     

沼渣化学成分研究

采用硅胶、凝胶柱层析方法对鸡场沼渣甲醇提取物化学成分进行分离纯化,并结合波谱方法分析鉴定得到6个化合物,分别是:β-谷甾醇(1)、22β-羟基-12-齐墩果烯-3-酮(2)、21β-羟基-β-白檀酮(3)、29-羟基-12-土当归烯-3,22-二酮(4)、17β-雌二醇(5)和S(-)-雌马酚(6)。这些成分均首次从鸡场沼渣中分离得到。有研究表明,21β-羟基-β-白檀酮在IC5027.4μM就具有很好的抗肠贾第虫(Giardia intestinalis)活性。许多流行病学研究和动物实验、体外实验表明,S(-)-雌马酚有助于妇女更年期症状的改善、保护心血管、缓解骨质疏松症及抗乳腺癌、前列腺癌等保护作用。     

沼渣与污泥混合高温堆肥效果及氮素控制

以锯木屑为调理剂,以Mg(OH)2与H3PO4的混合液为高温堆肥过程中的氮素抑制剂,研究沼渣与啤酒厂污泥混合堆肥效果。结果表明:混合物经好氧发酵处理后,均达到腐熟。添加氮素固定剂处理和对照处理的最高温度都可达65℃以上,在堆肥过程中添加氮素固定剂处理可提高堆体中有机物质的转化速率,对氮素的固定率达18%以上,添加固氮剂处理的堆肥结束后P元素增加了51%,堆肥品质得到了大幅度提高。堆肥过程中的物料的种子发芽指数不断提高,达到0.9;添加固氮剂的处理堆肥的种子发芽指数为1.0,明显高于对照。可见采用高温堆肥和氮素固定技术可有效地实现沼渣及啤酒厂污泥的混合资源化,该研究为后期沼渣和啤酒厂污泥堆肥的规模化应用提供了技术参数。     

耐高温沼渣降解菌的筛选及复合菌剂降解效果研究

分离筛选耐高温纤维素降解细菌，构建可快速降解沼渣的复合菌剂，缩短堆肥腐熟时间。采用高温富集筛选法，从宁夏中卫市秸秆堆和畜禽粪便中分离筛选耐高温细菌，经羧甲基纤维素钠水解试验和滤纸条崩解试验复筛获得具有纤维素降解能力的菌株。通过纤维素酶和木质素酶活性比较，确定目标菌株并进行分类鉴定。开展拮抗性试验和菌种复配，构建复合型菌剂；经沼渣堆肥场地试验验证复合菌剂的促腐熟效果。本研究筛选获得2株耐高温纤维降解细菌——蜡样芽胞杆菌(Bacillus cereus)W44菌株和解蛋白芽胞杆菌(Bacillus proteolyticus)X51菌株，纤维素酶活性分别为34 812.69 U/L和34 159.10 U/L。比较菌株W44/X51配比分别为1:1、1:2和2:1的复合菌剂对沼渣堆肥的促腐熟效果，添加不同的复合菌剂均缩短了沼渣堆肥腐熟时间，其中1:2处理腐熟时间最短，较CK提前18 d。蜡样芽胞杆菌W44和解蛋白芽胞杆菌X51按1:2配比的复合菌剂可用于沼渣快速堆肥发酵。     

不同生态条件下长期施钾对土壤钾素固定影响的机理

采用X射线衍射分析技术和室内模拟法,研究了长期施钾对不同生态条件和不同轮作制度下黑土、塿土和灰漠土钾素固定的影响机理.结果表明,长期施钾对水云母含量较低土壤的钾素固定能力影响较大.与不施钾土壤相比,水云母含量较低的黑土和含量较丰富的塿土在外源钾加入浓度在400～4000 mg·kg^-1范围内,对外源钾的固定量分别降低了75～747mg·kg^-1和16～238 mg·kg^-1,而水云母含量丰富的灰漠土的固钾能力无明显变化.长期施钾主要通过影响土壤含钾矿物组成对土壤固钾能力产生影响,即延缓或阻止水云母向云母-蒙脱石混层层间矿物的转化,使土壤对外源钾的固定能力降低;另外,长期施钾使土壤缓效钾含量和K⁺饱和度增加,土壤固钾能力降低.     

秸秆还田对土壤钾素的影响及其替代钾肥效应研究进展

农作物秸秆是重要的有机资源,其合理有效利用也越来越受到重视。秸秆还田具有增加作物产量、提高土壤有机碳含量、培肥地力、促进养分循环利用和缓解土壤酸化等特点,对减少化肥施用具有重要作用。随着人们对资源高效利用认识的深入,秸秆还田水平正在不断的提高,国内外在秸秆还田对土壤钾素影响等方面的研究也取得了丰硕的成果。本文主要从秸秆还田对土壤钾素、作物产量的影响以及秸秆钾素与化肥钾的等效性等方面对秸秆还田的钾素效应进行了综述。还田秸秆初期主要是通过自身钾素释放提高当季土壤速效钾含量,而长期秸秆还田还可能促进矿物钾的释放;有效的秸秆还田不仅能够为土壤提供大量氮、磷、钾等速效养分,而且能为土壤中的微生物提供丰富的碳源,提高土壤肥力,进而增加作物产量。中国目前秸秆有效还田仍然不足1/3,与欧美国家秸秆还田率相比还具有很大的发展潜力。加强秸秆还田率将能缓解中国耕地土壤钾素缺乏与钾矿资源不足的矛盾。今后应进一步深入研究适宜秸秆还田量及其与化肥钾的合理配置,短期试验结合长期监测以探讨秸秆还田对钾素影响的作用机理,为提高秸秆有效还田,促进土壤-作物钾素高效循环提供理论依据。     

饥饿对日本沼虾摄食节律的影响

本文研究了不同饥饿时间对开本沼虾Macrobrachium nipponense摄食节律的影响.结果表明,饥饿后恢复投饵初始日本沼虾表现出强烈的摄食,摄食节律为单峰型,随着时间的延长,多峰型摄食节律出现.饥饿4 d的日本沼虾在饥饿过程中并未出现饥饿死亡现象,恢复投喂后在较短时间内(5 d)即可恢复正常的摄食节律.饥饿8 d组在饥饿的第6～8 d便可明显观察到虾体色异常并有部分死亡,说明饥饿8 d已经影响到了日本沼虾的存活.饥饿8 d组日本沼虾摄食高峰的变化无明显规律,恢复到正常摄食节律需要较长时间.     

温度对罗氏沼虾亲虾代谢的影响

罗氏沼虾［Ｍａｃｒｏｂｒａｃｈｉｕｍｒｏｓｅｎｂｅｒｇｉ（ＤｅＭａｎ）］具有较高的经济价值,为当今世界上淡水虾类养殖的主要品种之一。由于我国没有天然的亲虾资源,人工育苗所需的亲虾靠养殖和人工越冬所得。因此研究亲虾的生理生态,可为提高人工繁殖技术的理论...     

沼气发酵残余物应用于金丝小枣栽培的初步研究

通过田间试验比较了沼气发酵残余物（沼渣和沼液）和化肥对金丝小枣部分形态特征、土壤肥力和果实品质等的影响.结果表明,施用沼渣和沼液能显著增强植株和枣果抗病、抗逆能力;改良土壤肥力状况,有机碳、总氮和矿质氮分别比化肥组对照高42.65%、37.61%和35.26%;降低土壤碱度,土壤pH值由875下降到821;增加土壤微生物量,微生物碳和氮量分别比对照高59.44%和56.06%;提高果实品质,其中粗纤维、维生素C、总氨基酸、微量元素铁和磷的含量分别比对照高27.69%、24.85%、19.81%、10.89%和5.26%.表明将沼气发酵残余物应用于金丝小枣栽培能给枣农带来良好的经济收益和环境效益,为金丝小枣的无公害生产提供了新思路.     

Estimation of available potassium for cotton by soil analysis

Measurements of exchangeable K, percentage of exchangeable K of the total exchange capacity (EPP), K extracted in a CaCl₂ solution, and the change in free-energy of exchange of K for Ca+Mg (F), were compared as methods for estimation of available K in soil for growing irrigated cotton. A significant correlation was found between each of the methods and the response to K fertilizer. The different methods are discussed; the advantages of extraction with CaCl₂ solution are that it reflects the change in free energy and is easy to operate. For sandy soils, it is suggested that determination of exchangeable K be added.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1975 Series, No. 202-E Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 1975 Series, No. 202-E     

Availability of Mn as affected by carbonate addition

Summary Addition of CaCO₃ to the soils has been found to increase the retention of manganese applied to soils. As the black soil contained enough of CaCO₃ initially the addition of CaCO₃ even upto 16% is not effective. But in red soil the effect in marked.It has also been observed that addition of CaCO₃, at the rate of 1 to 8 per cent to H-soils, resulted in an increased retention of manganese.The E and r forms decrease and increase respectively with an increase in the addition of CaCO₃ addition to both original and H-soils.Addition of soluble carbonates has also been found to effect the retention of manganese.The availability of manganese added to soils in the soluble form has been found to be adversely affected by the addition of both soluble and in soluble carbonates to black, red, and alkali soils.     

施钾量和施钾时期对小麦氮素和钾素吸收利用的影响

利用¹⁵N示踪技术,研究了施钾量和施钾时期对高产小麦氮素和钾素吸收利用的影响.结果表明： 0～20 cm土层土壤速效钾含量为118.5 mg·kg^-1时,一次性基施钾肥未提高植株的氮、钾积累量;速效钾含量为79.0 mg·kg^-1时,施钾显著提高了植株的氮、钾积累量.采用分期施钾时（1/2基施、1/2拔节期追施）,随施钾量增加,小麦吸收的肥料氮和土壤氮量及追施氮肥在土壤中的残留量均增加,肥料氮的损失量降低.分期施钾显著提高了植株的氮、钾积累量、吸收效率和生产效率,当施钾量为135 kg·hm^-2时,与一次性施钾相比,分期施钾促进了植株对追肥氮和土壤氮的吸收,提高了追施氮肥在土壤中的残留量.结果还表明：施钾提高了小麦的籽粒产量、蛋白质含量和湿面筋含量;分期施钾处理优于一次性施钾处理,以K45+45（45 kg·hm^-2基施、45 kg·hm^-2拔节期追施）处理最优.过多施钾使小麦产量和品质趋于降低.     

Availability of phosphorus in a calcareous soil treated with rock phosphate or superphosphate as affected by phosphate-dissolving fungi

A study was undertaken to isolate some fungi exhibiting phosphate-dissolution ability, and to test whether these fungi are capable of increasing the amount of available P in a calcareous soil treated with rock phosphate (RP) or with triple superphosphate (TSP) and its subsequent uptake by sorghum (Sorghum bicolor L. Moench).Penicillium sp. and twoAspergillus foetidus (Naka) isolates significantly increased the availability of P in soil treated with RP or TSP during the growing season.Penicillium sp. isolate was more effective in increasing available P in the soil treated with RP or TSP than were Aspergillus isolates. However, the dry matter and P uptake responses to inoculation with these fungi were better in the soil treated with RP than in soil treated with TSP. In the TSP treated soil, the fungi achieved their maximum P releasing capacity two weeks earlier than in soil treated with RP. Positive and significant correlation coefficients among available P, P uptake and dry matter production at different periods of the growing season were observed following inoculation. However, none of these variables were found to be significantly correlated with the fungal populations.     

Utilization of by-products from ethanol production as substrate for biogas production

The aims of this work were to determine the specific biogas yields of steam-exploded sugarcane straw and bagasse as well as to estimate their energy potential under Brazilian conditions. Steam-explosion was carried out under different time and temperature conditions. The specific biogas yields were analyzed in batch-tests according to VDI 4630.Results have shown that steam-explosion pre-treatment increased the specific biogas yields of straw and bagasse significantly compared to the untreated material. The utilization of these by-products can contribute to 5% of the total energy consumption and thereby higher energy independence in Brazil. Further efforts in defining the optimum pretreatment conditions with steam-explosion as well as implementing this technology in large scale plants should be made.     

Nitrogen mineralization and denitrification as influenced by crop residue particle size

Managing the crop residue particle size has the potential to affect N conservation in agricultural systems. We investigated the influence of barley (Hordeum vulgare) and pea (Pisum sativum) crop residue particle size on N mineralization and denitrification in two laboratory experiments. Experiment 1: ¹⁵N-labelled ground (3 mm) and cut (25 mm) barley residue, and microcrystalline cellulose+glucose were mixed into a sandy loam soil with additional inorganic N. Experiment 2: inorganic¹⁵ N and C₂H₂ were added to soils with barley and pea material after 3, 26, and 109 days for measuring gross N mineralization and denitrification.Net N immobilization over 60 days in Experiment 1 cumulated to 63 mg N kg^-1 soil (ground barley), 42 (cut barley), and 122 (cellulose+glucose). More N was seemingly net mineralized from ground barley (3.3 mg N kg^-1 soil) than from cut barley (2.7 mg N kg^-1 soil). Microbial biomass peaked at day 4 with the barley treatments and at day 14 with the cellulose+glucose whereafter the biomass leveled out at values 79 mg C kg^-1 (ground), 104 (cut), and 242 (cellulose+glucose) higher than for the control soil. Microbial growth yields were similar for the two barley treatments, ca. 60 mg C g^-1 substrate C added, which was lower than the 142 mg C g^-1 C added with cellulose+glucose. This suggests that the 75% (w/w) holocelluloses and sugars contained with the barley material remained physically protected despite grinding. In Experiment 2 gross mineralization on day 3 was 4.8 mg N kg^-1 d^-1 with ground pea, twice as much as for all other treatments. On day 26 the treatment with ground barley had the greatest gross N mineralization. In static cores ground barley denitrified 11-fold more than did cut barley, whereas denitrification was similar for the two pea treatments. In suspensions denitrification was similar for the two treatments both with barley and pea residue.We conclude that the higher microbial activity associated with the initial decomposition of ground plant material is due to a more intimate plant residue-soil contact. On the long term, grinding the plant residues has no significant effect on N dynamics.     

Glycoalkaloid and nitrate content of potatoes as affected by method of selenium application

A comparison of two methods of selenium application, banding and foliar spray, of sodium selenite (Na₂SeO₃) on total glycoalkaloid (TGA) and nitrate nitrogen (NO₃-N) was studied during each of two consecutive years. The levels of application used were 0.0, 1.6 (0.75), 3.36 (1.5), and 5.6 (2.5) kg/ha (ppm soil). Both TGA and NO₃-N were significantly reduced by application of 1.5 and 2.5 ppm of sodium selenite. Tuber selenium levels were significantly increased at all levels of application, using either banding or foliar spray, but were well below the toxic range for human consumption. Banding resulted in greater uptake of Se, and greater decreases in TGA and NO₃-N as compared to foliar spray.     

Decomposition of wheat straw and rye residues as affected by particle size

Effects of contact between the soil and crop residues on the processes of residue decomposition are still poorly understood. The objective of this study was to investigate the effects of residue particle size on the decomposition of wheat (Triticum aestivum L.) straw (C/N=270) and green rye (Secale cereale) residues (C/N=9). Residue particle size was used as a means to vary the contact between crop residues and the soil. Carbon mineralization was measured during 102 d for straw and 65 d for rye, on residues ranging in sizes from laboratory model (0.03 cm) to field-scale (10 cm). The soil was a silt (Typic Hapludalf) and the incubation was performed at 15 °C. The effects of particle size on C mineralization varied for the two residues. In the first two days of incubation, decomposition rate of rye increased with decreasing particle size but thereafter, the trend was reversed. In 65 days, 8% more C was decomposed in the 7-cm residues than in the 0.03-cm ones. For wheat straw, early decomposition (3–17 days) was faster for the small-sized particles (0.06 and 0.1 cm). Thereafter, the largest size classes (5 and 10 cm) decomposed faster. After 102 days, the very fine particles ( 0.1 cm) showed the greatest and the intermediate size classes (0.5 and 1 cm), the lowest amount of C mineralized. We hypothesized that greater availability and accessibility of N was responsible for the higher rates of decomposition observed for finely-ground wheat straw while a physical protection of finely ground residues was probably involved in the observed reverse effect for rye.     

Nitrogen metabolism of young barley plants as affected by NaCl-salinity and potassium

Summary In a solution culture experiment with 31 days old barley plants (var. Miura) the influence of NaCl-salinization (80 mM) and KCl addition (5 and 10 mM) on the uptake and turnover of labelled nitrogen (¹⁵NH₄ ¹⁵NO₃) was studied. Labelled N was applied for 24 h at the end of a 20 days' salinization period. Salinization impaired growth and incorporation of labelled N into the protein fraction paralleled by accumulation of labelle dinorganic N. All salt effects were much more pronounced in the shoots than in the roots.Potassium addition enhanced N uptake (total¹⁵N-content) and incorporation into protien, reduced the accumulation of inorganic N and improved the growth of salinized plants.The presented data support the point of view that impairment of protein (enzyme) metabolism is an important aspect of salt stress which is probably induced by the disturbance of the K/Na balance of the tissues under saline conditions.This work was supported by a grant from the Alexander von Humboldt foundation.