Straw management and tillage effects on soil water storage under field conditions

Abstract. A two year field study was conducted to evaluate the effects of straw management and tillage on the soil profile (1.5m) water storage, nature of the moisture profile, infiltration and sorptivity as influenced by rainfall, evaporativity (E₀) and soil texture. The straw mulch treatment stored more moisture under low E₀ rainy conditions in three coarse to medium textured soils. Straw incorporation treatment was better under low E₀ rain free conditions, as well as under high E₀ rainy conditions in the two coarser textured soils. In the coarsest textured soil, tillage and straw mulching were not effective in maintaining greater soil water storage under high E₀ because of the very open nature of the soil. The soil moisture profiles showed a sharper increase in water content below the tilled layer in the tillage and straw- incorporation treatments than the untreated and straw mulch treatments. Tillage and straw incorporation treatments increased the sorptivity of the soil compared with untreated and straw mulch treatments respectively. The results of this study suggest that when selecting a suitable soil water conservation practice to increase water storage in the soil profile, information on soil texture and weather (rain and evaporativity) must be considered.     

稻草还田和冬种绿肥对华南双季稻产量及稻田CH4排放的影响

以常规稻合丰占为材料,开展田间裂区试验,主因素设稻草不还田和全部稻草还田2种处理,副因素设冬闲和冬种绿肥并全部还田2种处理,研究稻草还田和冬种绿肥及其互作对华南双季稻产量和稻田CH4排放的影响,以期为华南双季稻低碳高产栽培提供指导。结果表明:稻草全量还田显著提高水稻产量,平均增产4.8%,主要原因是稻草还田促进水稻的干物质积累,增加了每穗粒数,但稻草还田极显著增加稻田CH4排放量,平均增幅为41.8%;冬种紫云英绿肥显著提高水稻产量,平均增产3.6%,同时稻田CH4排放量也增加,但差异没有达到显著水平。无论是对水稻产量还是稻田CH4排放,稻草还田和冬种绿肥处理之间的互作效应均不显著,表明二者的作用是相互独立的。综合考虑水稻产量和CH4排放的表现,冬种紫云英绿肥可作为华南双季稻低碳高产栽培的重要措施。     

The difference in N metabolism between NAD(P)H-specific NR-deficient mutant and wild-type barley (Hordeum vulgare L.)

Abstract

Barley (Hordeum vulgare L.) is an important crop for cereal research. In this study, two barley genotypes the wild-type (Steptoe) and the mutant (Az12) were used. An experiment was conducted using ¹⁵N-tracing method to NADH-specific nitrate reductase (NR)-deficient mutant seedling of barley. The N-depleted seedlings were exposed to a nutrient solution containing nitrate and nitrite, and were labeled with ¹⁵N for 38?h under (14?L/10D) cycles. The two genotypes utilized ¹⁵NO₃^? and accumulated it as reduced ¹⁵N, predominately in the shoots. However, nitrate reduction in the Az12 shoots was 9% lower than that in the Steptoe shoots at 38?h. As a result, in the Az12, nitrate accumulation in shoots was 78% higher than that in the Steptoe. Accumulation of reduced ¹⁵N in the Az12 roots was nearly similar to that of the Steptoe roots, but 8% lower in the Az12 shoots than in the Steptoe shoots at the end of the experiment. Also for both genotypes, root contribution increased during L/D cycles and decreased during the subsequent light cycle. Upward transport of reduced ¹⁵N via the xylem in the Az12 was nearly two times higher than that in Steptoe during the second light period (24–38?h). In both genotypes, xylem transport of reduced ¹⁵N was far exceeded the downward phloem transport. Abbreviations Anl accumulation of reduced ¹⁵N from ¹⁵NO₃^? in non-labeled roots of split roots

Ar accumulation in roots of reduced ¹⁵N from ¹⁵NO₃^?

As accumulation in shoots of reduced ¹⁵N from ¹⁵NO₃^?

Rr ¹⁵NO₃^? reduction in roots

Rs ¹⁵NO₃^? reduction in shoots

Tp translocation to root of shoot reduced ¹⁵N from ¹⁵NO₃^? in phloem

Tx translocation to shoot of root-reduced ¹⁵N from ¹⁵NO₃^? in xylem

FW fresh weight

     

Incorporation of 14CO2 and 15NH4 into amino acids of the two subunits of fraction 1 protein in spinach leaves

In the investigation of nitrogen metabolism in plants, it is important to deal with proteins, which are the end-products of nitrogen metabolism.     

The Effect of Nitrogen Catch Crops on the Nitrogen Nutrition of a Succeeding Crop: I. Effects through Mineralization and Pre-emptive Competition

Abstract

The effects of catch crops on the nitrogen nutrition of a succeeding carrot crop were investigated. An attempt was made to distinguish the effects of growth and nitrogen uptake by the catch crop from the effect of mineralization of its residues. It was found that growth and nitrogen uptake by catch crops could reduce the nitrogen supply to the succeeding carrot crop through pre-emptive competition, whereas mineralization of nitrogen from the catch crop residues increased the nitrogen supply to the carrot crop. Nitrogen uptake by the carrots was thus highest where catch crop residues were incorporated on plots where no catch crop had been grown. The effect of the mineralization was found mainly to influence topsoil mineral nitrogen contents and the early nitrogen uptake by carrots, whereas the effect of pre-emptive competition was to reduce subsoil mineral nitrogen content and the nitrogen uptake by carrots late in the growing season. The apparent recovery of catch crop nitrogen by carrots was between 8 and 33%.     

不同栽培方式和秸秆还田对水稻产量和营养品质的影响

为阐明水稻产量和营养品质在不同栽培方式和秸秆还田条件下的表现特性, 以两优培九(籼稻)为材料, 常规水作(CFC)为对照, 通过长期定位试验(2001—2010年)研究了覆膜旱作(PFMC)、裸地旱作(NMC)和秸秆还田对水稻产量、精米中蛋白质和氨基酸、糙米中铁和锌含量的影响。2008—2010三年试验结果(平均值)表明, 与CFC相比, PFMC能显著增加水稻产量, 增产幅度达8.0%, 精米中总氨基酸含量下降3.5%, 精米中蛋白质, 糙米中铁锌含量与CFC处理差异不显著; NMC处理产量显著下降5.1%, 蛋白质、总氨基酸和铁含量分别下降4.4%、9.3%和11.9%。秸秆还田较不还田处理, CFC条件下, 产量增加了113.6 kg hm^-2; NMC条件下, 产量增加142.6 kg hm^-2; PFMC条件下, 产量增加522.1 kg hm^-2; 三种栽培方式产量平均增加3.3%, 糙米中的铁和锌含量平均增加3.1%和6.4%, 精米中蛋白质和总氨基酸含量差异不显著。本试验结果表明, PFMC能显著提高水稻产量, 秸秆还田能显著提高水稻产量和稻米中铁、锌含量。     

玉米螟杀虫剂的室内筛选

[目的]筛选对玉米螟幼虫和卵具有较好毒杀作用的药剂,为玉米螟的化学防治提供科学依据。[方法]采用人工饲料混药法和浸渍法分别测定10种杀虫剂对玉米螟幼虫和卵的毒杀作用。[结果]印楝素、甲维盐和氯虫苯甲酰胺对玉米螟幼虫具有较高毒力,对3龄幼虫的加50值分别为0．0006,0．0250和0．0387mg／L;印楝素浓度为10．0mg／L时,卵的孵化率为17．80％。[结论]印楝素、甲维盐和氯虫苯甲酰胺可作为玉米螟的防治药剂。     

机械化稻草全量还田对水稻产量和土壤碳库管理指数的影响

通过设置不施肥、单施化肥、稻草烧灰还田+化肥和稻草全量还田+化肥4个处理的大田定位试验,在氮、磷和钾养分相等条件下研究稻草全量还田对双季水稻产量和土壤碳库管理指数的影响。结果表明,晚稻稻草全量还田有利于提高翌年早稻产量,较单施化肥与稻草烧灰还田相比,增幅3.4%～4.3%,而晚稻产量稻草全量还田处理与单施化肥基本持平,却显著低于稻草烧灰还田处理;与单施化肥和稻草烧灰还田相比,稻草全量还田提高了土壤不同形态碳素含量和碳库管理指数,活性碳、矿化碳和碳库管理指数分别提高了5.93%～7.87%、27.14%～67.55%和11.41%～21.49%。相关分析表明,土壤碳库管理指数与双季早、晚稻产量呈显著抛物线关系(r=0.982 9*和r=0.982 8*)。     

稻草还田和易地还土对红壤丘陵农田土壤有机碳及其活性组分的影响

 【目的】探讨稻草还田和易地还土对红壤丘陵水田和旱地土壤有机碳及活性有机碳的影响。【方法】以红壤丘陵区长期定位点坡旱地和水旱轮作地为研究对象,选取3个处理：不施肥（CK）、单施化肥（NPK）和稻草配施氮磷肥（S+NP）,对试验6年来的数据进行分析。【结果】与初始值相比,坡旱地NPK和S+NP处理在前4年内土壤有机碳（SOC）明显增加,平均增幅分别为14.6%和36.2%,此后波动较小;微生物量碳（MBC）总体保持增加趋势,NPK和S+NP处理显著高于CK,平均增幅分别为16.1%和33.5%;溶解有机碳（DOC）保持逐年增加,处理间差异不显著。水旱轮作地各处理土壤有机碳6年内基本保持稳定,但NPK和CK处理均低于初始值;MBC总体亦具有增加趋势,S+NP处理明显高于CK,平均增幅为 14.2%,但NPK处理低于CK;DOC后期出现降低趋势,且NPK和S+NP处理均低于CK。【结论】与单施化肥相比,稻草还田和易地还土均能明显提高土壤SOC和MBC含量,但稻草易地还土的效果更为显著,并在短期内表现明显。土壤溶解有机碳对施肥的响应较差,耕作时间较短的坡旱地土壤溶解有机碳含量明显高于耕作时间较长的水旱轮作地。     

麦秸还田对土壤理化性质及酶活性的影响

 【目的】探讨麦秸秆还田对水稻土壤理化性质和酶活性的影响及其相互关系。【方法】粳稻扬粳9538种植于大田,进行了麦秸还田与不还田、实地氮肥管理（SSNM）和农民习惯施肥法（FFP）等处理,观察了秸秆还田后水稻不同生长阶段的土壤pH值、有机酸含量、呼吸速率、土壤酶活性及土壤离子的变化动态。【结果】秸秆的腐解高峰在水稻生长的第1个月,土壤中有机酸含量在分蘖中期及穗分化期明显上升;土壤脲酶及过氧化氢酶活性表现为先升后降,而碱性磷酸酶活性则表现为双峰曲线的变化规律。秸秆还田后土壤pH值明显降低,有机酸含量增加,并且两者之间呈极显著的负相关关系,土壤中脲酶、过氧化氢酶及碱性磷酸酶活性增强,土壤全磷、可溶性钾含量明显上升,但Na+、Mg2+及Ca2+含量降低,土壤中酶活性和离子含量的升降与土壤中秸秆的腐解有关。秸秆还田增加了水稻成熟时土壤有机质含量及呼吸强度。与实地氮肥管理（SSNM）相比,农民习惯施肥法（FFP）处理增加了土壤中脲酶活性,对其它指标无显著性影响。土壤脲酶和碱性磷酸酶活性与土壤中有机质、全氮、全磷及全钾含量呈极显著正相关,土壤过氧化氢酶及土壤有机质与全氮呈正相关,与全磷、全钾相关不显著。【结论】秸秆还田能够增强土壤有机质含量与土壤酶活性,降低土壤中Na+、Mg2+及Ca2+含量,提高土壤肥力。