黑土农田养分供应能力和变化

本文通过５年的定位试验研究结果表明：松嫩平原典型黑白农田养分自然供给力Ｎ素为９０％左右，Ｐ素为９５％以上，Ｋ素达到１００％。农田土壤中Ｎ素的释放量一般５５－９９ｋｇ／ｈａ．ａ，Ｐ素的释放量一般１４－２６ｋｇ／ｈａ．ａ．，Ｋ素的释放量一般４８－９３ｋｇ／ｈａ．ａ。尽管黑土农田潜在肥力很高，对于施肥的依赖性也在不断增加。     

筒栽冬小麦施用控释氮肥增产效应的研究

试验研究筒栽冬小麦施用 2种控释N肥结果表明 ,相同灌水量和灌溉次数、施等N量下 ,与施用普通尿素(F1)相比冬小麦施用乐喜施控释N肥 (F2 )和众品控释N肥 (F3 )处理产量均显著提高 ,N素表观利用效率分别提高5 %～ 10 % (I1)和 13%～ 2 6 % (I2 ) ,对冬小麦扎根深度和总根重显著影响为F1相似文献   

藻类生长对滇池沉积物磷释放影响的研究

室内对滇池沉积物进行藻类生长模拟试验,结果表明,以沉积物作为唯一P源进行培养,滇池藻类依然可以正常生长;沉积物在藻类生长的影响下,具有较强的P释放潜力,释放速率可达19.2mg/(m2·d);藻类生长对P的大量需求,是通过OH-对沉积物Fe结合态P阴离子置换,和对金属离子Fe的有机蝥合以增加被结合态P的解吸两种主要途径获得的,藻吸收利用沉积物中P的形态主要为Fe结合态P。     

福州茉莉花种植园土壤化学计量比及其对碳释放潜力的影响

选取有机茉莉花种植园、常规茉莉花种植园、茉莉花+龙眼间作种植园为研究对象,通过测定3种种植园土壤全碳(TC)、全氮(TN)、全磷(TP)、全钾(TK)质量分数及二氧化碳(CO2)释放潜力,研究不同种植方式下茉莉花种植园土壤化学计量比及其对碳释放潜力的影响。结果表明:1)3种茉莉花种植园土壤碳氮质量比值(C/N)分别为11.33、10.93、9.48,碳磷质量比值(C/P)为23.23、25.33、10.91,碳钾质量比值(C/K)为1.02、0.88、1.66,氮磷质量比值(N/P)为2.05、2.32、1.14,氮钾质量比值(N/K)为0.09、0.08、0.17,磷钾质量比值(P/K)为0.04、0.03、0.15;2)3种茉莉花种植园土壤C/N表现为有机茉莉花种植园>常规茉莉花种植园>茉莉花+龙眼间作种植园,有机茉莉花种植园土壤N/P显著低于常规茉莉花种植园,土壤P/K则相反,茉莉花+龙眼间作种植园土壤C/P、N/P显著低于常规茉莉花种植园,土壤C/K、N/K、P/K则相反;3)3种茉莉花种植园土壤CO2释放潜力分别为5.80、3.79、4.92μg/(g·d),但差异性均不显著,茉莉花+龙眼间作种植园土壤C/P、C/K、N/P、N/K对CO2释放潜力的剖面变化具有一定指示作用,间作-有机种植相结合是福州茉莉花种植系统较合理的种植模式。     

控释肥在盆栽棉花上的肥效研究

采用包膜控释肥进行了棉花盆栽试验,并以普通复合肥作对照研究包膜控释肥对棉花的增产效应。研究结果表明,与普通复合肥相比,施用控释肥更有效提高了土壤中硝态氮和铵态氮及其速效磷、速效钾含量,经控释肥处理的棉花叶绿素相对含量、株高均比普通复合肥有明显的优势。控释肥对棉花的果枝数、桃数在各施肥水平上与普通复合肥相比不显著,包膜控释肥施用纯氮量分别在0.2,0.4 g/kg土时比相同施氮量普通复肥具有显著的增产作用,相对增产率分别为113.1%和34.5%,而且在施用量减少的情况下,仍能获得高于普通复肥的产量。控释肥比普通复肥具有控制释放,提高产量和降低施肥量的优越性。     

2种缓/控释肥对滨海盐碱地区水稻产量及氮代谢的影响

为实现节本增效稻作,缓解大量、多次追肥引发不良环境效应,以中晚熟粳稻"盐丰47"为试材,设常规化肥、中科虹稳定性复合肥、炭基肥料3种处理及空白对照组,研究缓/控释肥对水稻生长发育、氮代谢酶活性及产量构成的影响。结果表明,施用2种新型肥料的产量与常规处理相比无显著差异。从产量构成来看,中科虹稳定性复合肥和常规化肥高产主要归因于较多的有效穗数,而炭基肥料依靠较高水平的穗粒数、结实率和千粒重维持产量;从氮代谢角度分析,2种新型肥料提高了齐穗期水稻功能叶硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、亚硝酸还原酶(NiR)活性及可溶性蛋白含量,而常规处理谷氨酸合成酶(GOGAT)活性显著高于其他处理和空白对照组。中科虹稳定性复合肥中硝化抑制剂、脲酶抑制剂等组分保证了较长的养分释放周期,改善了植株生长关键阶段氮代谢能力,特别是分蘖末期起保蘖增穗的作用;而炭基肥料中生物炭等有效组分增强了土壤养分固持能力,提高了可提取态养分含量及其有效性。因此,科学施用中科虹稳定性复合肥和炭基肥料可在稳产基础上减少化肥用量(较常规处理分别减少151.50,187.50 kg/hm~2),对肥料投入较高的滨海盐碱地区发展绿色可持续农业具有应用价值。     

硒酸根与氢氧根离子在可变电荷土壤表面的交换反应: Ⅱ. 氢氧根离子释放的动力学

A self-made constant pH automated titration instrument was used to study the kinetics of hydroxyl release during selenite reacting with variable charge soils. The rate of hydroxyl release was very rapid at the first several minutes, then gradually slowed down, and at last did not change any more. The experimental data was well fitted by the Langmuir kinetic equation, and with increasing selenite concentration or decreasing solution pH, the reaction lasted longer, the maximum of hydroxyl release (x_m) increased, and the binding constant (k) decreased. The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.     

Impact of rainfall regime on the decomposition of leaf litter with contrasting quality under subhumid tropical conditions

In alley-cropping systems, hedgerow trees are regularly cut back. Losses of N released from the decomposing prunings are minimized when N release is synchronized with crop N demand. In this study, the sensitivity of the decomposition of Leucaena leucocephala, Senna siamea, and Dactyladenia barteri leaf litter to the nature of the rainfall regime is correlated with the residue quality. The litterbag technique was used to measure decomposition. Four periods of 115 days, each starting at a time when hedgerow trees are normally pruned, were selected and the rain that fell during each of these periods in 1986 was simulated on a day-to-day basis by applying irrigation water on the litterbags. The number of rainfall events was better correlated with the percentage dry matter loss than with the total amount of precipitation. The relationship consisted of two lines. The slope of the first line, indicative of the sensitivity of the decomposition to varying numbers of rainfall events, correlated well with the watersoluble fraction (P<0.05), the C:N ratio (P<0.05), and the polyphenol: N ratio (P<0.01) of the residues. The decomposition process was shown to be dominated by microbial catabolism, rather than leaching. Because the decomposition of the higher quality residues is affected by varying rainfall patterns and because rainfall may often be unpredictable in frequency and intensity, synchronization of N released from a significant part of the decomposing residue with crop N demand may require additional management practices.     

缓/控释肥对小麦增产与提高氮肥利用率的效果研究

以不施氮肥、尿素基施和尿素基追比5:5等3个处理做对照,对3种包膜缓/控释肥处理冬小麦产量、产量相关因子、不同时期植株含氮量及肥料利用率进行了分析比较。结果表明,缓/控肥处理的以上几个指标均接近于尿素基追比5:5处理。与尿素基施相比,包膜缓/控释肥增产10.03%～11.17%,有效穗数和穗粒数增加,返青-拔节期植株含氮量明显提高,氮肥利用率提高了6.18%～11.57%。3种缓/控释肥相比较,产量、产量因子、植株含氮量及肥料利用率没有显著性差异。     

有机酸根对不同土壤组分无机磷生物有效性的影响

A field investigation was conducted to determine the survival and growth rate of eucalyptus (Eucalyptus camaldulensis Dehn.) and guava (Psidium guajava L.) saplings planted in salt-affected soils. The field used was highly saline-sodic in nature with a wide variation in electrical conductivity of the saturated soil extract (ECe), pHs, sodium adsorption ratio (SAR) and gypsum requirement (GR). A randomized complete block design was utilized with three treatments, i.e. T1=plastic container bags totally removed, T2=only the plastic container bag‘s base removed and T3=plastic container bags un-removed. There were 34 and 8 plants in each block for eucalyptus and guava, correspondingly. The survival rates of eucalyptus and guava saplings were greater than 90%. In addition, gain in eucalyptus height was significantly higher in the T1 treatment where the bags were totally removed while for guava height the treatments were not significant. The gain in girth was not significant for both eucalyptus and guava saplings. With eucalyptus the taproot length was greater than the lateral roots while for guava the lateral roots were longer than the taproots. There was a decrease in the salinity-sodicity of the soils for the upper 30 cm depth under both types of vegetation, indicating that the salts had leached down to the B-horizon.