Effect of Nitrogen Applied Before Transplanting on NUE in Rice

Nitrogen （N） application before transplanting, where N fertilizers are applied in seedling-bed and carried to the paddy field with seedlings, is a novel method proposed in this article aiming for improving nitrogen utilization efficiency （NUE） in rice. The effect of this method on mineral N distribution in the rhizosphere soil was investigated in a field experiment with a japonica variety, Ningjing 2, in seasons of 2004 and 2005. There were four levels of N applied 16 h before transplanting： zero N （NO）, 207 kg ha^-1 （NL）, 310.5 kg ha^-1 （NM）, and 414 kg ha^-1 （NH）. The result indicated that N fertilizer before transplantation had positive effect of increasing mineral N content in the rhizosphere soil of rice. Generally, N content in the rhizosphere soil of rice tended to increase with the amount of N fertilizer before transplanting, with the NH treatment having the largest effect. Additionally, N fertilizer before transplanting had significant influence on rice NUE and grain yield. Compared with other treatments, the NM treatment showed the largest influence, with basal-tillering NUE, total NUE, and grain yield being 15%, 12%, and 529.5 kg ha^-1 higher than those of NO treatment. This result indicated that N fertilizer before transplantation had positive effect on mineral N distribution in the rhizosphere soil of rice, thus improving NUE and grain yield.     

Effects of Organic Fertilizer on Fruit Quality and Acidified Soil Chemical Properties in Yantai Orchard

Objective] This study aimed to investigate the improving effect of organic fertilizer on acidified soil as wel as their ef-fects on fruit quality and quantity in Yantai orchard. [Method] Plot experiment was conducted to investigate the effects of organic fertilizer on fruit yield and quality of Red Fuji and chemical properties of acidified soil. [Result] The apple yield in acidified soil applied with organic fertilizer al increased. Under the application of biological organic fertilizer, the apple yield was higher, and it was 8.92% higher than that in the control group. Under the mixed application of chemical fertilizer and biological organic fertiliz-er, the growth and development of apple trees were improved, and the total soluble solid (TSS) content, vitamin C (Vc) content and TSS-acid ratio in mature apples al increased. The application of organic fertilizer significantly reduced soil acidity. Compared with those in the control group, the soil pH value, organic matter content and alkali-hydrolyzable nitrogen content under the ap-plication of biological organic fertilizer were increased by 8.33%, 15.10% and 30.80%, respectively. [Conclusion] The application of biological organic fertilizer could improve the yield of apple in acidified soil.     

Application of Chinese milk vetch affects rice yield and soil productivity in a subtropical double-rice cropping system

Green manure can be used as a substitute for chemical fertilizer without reducing rice yield. We studied the responses of soil fertility and rice yield to different combinations of Chinese milk vetch(CMV; Astragalus sinicus L.) and chemical fertilizer in a subtropical double-rice cropping system. Our goal is to reduce chemical fertilizer use and decrease environmental contamination. Compared with the recommended rate of chemical fertilizer(CF), both early-and late-rice yields in the two treatments supplied with 15 and 22.5 Mg CMV ha–1 plus 60% CF(represented as 60 A and 60 B, respectively) showed no significant differences while the two treatments supplied with 30 and 37.5 Mg CMV ha–1 plus 60% CF(represented as 60 C and 60 D, respectively) showed significantly higher values. The sustainable yield index(SYI) values in the 60 C and 60 D treatments with double-rice croppong system were significantly higher than those in other treatments(P0.05). Early-rice yield showed a significant positive relationship with the Chinese milk vetch incorporation rate. The coefficients increased annually from 2009 to 2013 and then decreased in 2014. Soil organic matter increased over time by the end of the experiment in all of the treatment groups. Soil organic matter in 60 A, 60 B and 60 C showed no significant difference compared with that in CF, while soil organic matter in 60 D was significantly higher than that in CF. The slopes of soil organic matter and total nitrogen over six years were the highest in 60 C and 60 D. The soil total nitrogen content in 60 A, 60 B, 60 C and 60 D was higher than that in CF, but the differences were not significant(P0.05). Therefore, a relatively high Chinese milk vetch incorporation rate(≥30 Mg ha–1) was more effective in improving the productivity and sustainability of paddy soil. The decreased coefficients of early-rice yield and the Chinese milk vetch incorporation rate in 2014 implied that the benefits of soil fertility and rice yield created by Chinese milk vetch input may decline after five years under a continuously high rate of Chinese milk vetch incorporation.     

Effect of Long-Term Application of K Fertilizer and Wheat Straw to Soil on Crop Yield and Soil K Under Different Planting Systems

Effect of application of K fertilizer and wheat straw to soil on crop yield and status of soil K in the plough layer under different planting systems was studied. The experiments on long-term application of K fertilizer and wheat straw to soil in Hebei fluvo aquic soil and Shanxi brown soil in northern China were begun in 1992. The results showed that K fertilizer and straw could improve the yields of wheat and maize with the order of NPK ＋ St 〉 NPK 〉 NP ＋ St 〉 NP, and treatment of K fertilizer made a significant difference to NP, and the efficiency of K fertilizer in maize was higher than in wheat under rotation system of Hebei. In contrast with Shanxi, the wastage of soil potassium was a more serious issue in the rotation system in Hebei, only treatment of NPK ＋ St showed a surplus of potassium and the others showed a wane. K fertilizer and straw could improve the content of water-soluble K, nonspecifically adsorbed K, non-exchangeable K, mineral K, and total K in contrast to NP; however, K fertilizer and straw reduce the proportion of mineral K and improve proportion of other forms of potassium in the two locating sites. Compared with the beginning of orientation, temporal variability character of soil K content and proportion showed a difference between the two soil types; furthermore, there was a decrease in the content of mineral K and total K simultaneously in the two locating sites. As a whole, the effect of K fertilizer applied to soil directly excelled to wheat straw to soil. Wheat straw to soil was an effective measure to complement potassium to increase crop yield and retard the decrease of soil K.     

Effects of Organic Manure Application with Chemical Fertilizers on Nutrient Absorption and Yield of Rice in Hunan of Southern China

To evaluate the effect of organic manure application with chemical fertilizers on rice yield and soil fertility under long-term double-rice cropping system, a six year field experiment was conducted continually in the paddy soil derived from Quaternary red clay in Hunan Province of southern China. Four different treatments, i.e., no nitrogen with chemical P and K （PK）, swine manure only （M）, N, P and K chemical fertilizers only （NPK）, and half chemical fertilizers combined with half swine manure （NPKM） with four replications were included. Each N, P and K application rate was the same at all the treatments （except the N application rate at PK） and N application rate was 150 kg N ha^-1. All fertilizers were applied to soil tillage layer with once application as baseal fertilizers. The nutrients uptake rate, grain yield, nitrogen use efficiency, and soil organic matter content at each treatment were investigated. The NPKM treatment achieved the highest mean annual yield of 12.2 t ha^-1 （68% higher than that of PK）. Higher dry matter accumulation and nutrients absorption were observed during the middle-late growth period in the NPKM treatment, with higher panicle number per unit and filled-grain number per panicle. Its average nitrogen use efficiency was 36.3% and soil organic matter increased by 18.5% during the experimental period in the NPKM treatment, which were significantly higher than those in the NPK treatment. Organic manure application with chemical fertilizers increased the yield and nitrogen use efficiency of rice, reduced the risk of environmental pollution and improved soil fertility greatly. It could be a good practical technique that protects the environment and raises the rice yield in this region.     

Subsoiling and Ridge Tillage Alleviate the High Temperature Stress in Spring Maize in the North China Plain

High temperature stress（HTS） on spring maize（Zea mays L.） during the filling stage is the key factor that limits the yield increase in the North China Plain（NCP）.Subsoiling（SS） and ridge tillage（R） were introduced to enhance the ability of spring maize to resist HTS during the filling stage.The field experiments were conducted during the 2011 and 2012 maize growing seasons at Wuqiao County,Hebei Province,China.Compared with rotary tillage（RT）,the net photosynthetic rate,stomatal conductance,transpiration rate,and chlorophyll relative content（SPAD） of maize leaves was increased by 40.0,42.6,12.8,and 29.7% under SS,and increased by 20.4,20.0,5.4,and 14.2% under R,repectively.However,the treatments reduce the intercellular CO 2 concentration under HTS.The SS and R treatments increased the relative water content（RWC） by 11.9 and 6.2%,and the water use efficiency（WUE） by 24.3 and 14.3%,respectively,compared with RT.The SS treatment increased the root length density and soil moisture in the 0-80 cm soil profile,whereas the R treatment increased the root length density and soil moisture in the 0-40 cm soil profile compared with the RT treatment.Compared with 2011,the number of days with temperatures 33°C was more 2 d and the mean day temperature was higher 0.9°C than that in 2012,whereas the plant yield decreased by 2.5,8.5 and 10.9%,the net photosynthetic rate reduced by 7.5,10.5 and 18.0%,the RWC reduced by 3.9,5.6 and 6.2%,and the WUE at leaf level reduced by 1.8,5.2 and 13.1% in the SS,R and RT treatments,respectively.Both the root length density and the soil moisture also decreased at different levels.The yield,photosynthetic rate,plant water status,root length density,and soil moisture under the SS and R treatments declined less than that under the RT treatment.The results indicated that SS and R can enhance the HTS resistance of spring maize during the filling stage,and led to higher yield by directly improving soil moisture and root growth and indirectly improving plant water status,photosynthesis and grain filling.The study can provide a theoretical basis for improving yield of maize by adjusting soil tillage in the NCP.     

Effect of Enriched Cattle Manure on Soil Nutrient Status,Nitrogen Uptake and Yield of Tea （Camellia sinensis）

Inorganic fertilizer NPK （nitrogen, phosphorus and potassium） （S） 25：5：5：5 is generally recommended for optimum yield and quality of tea （Camellia sinensis）. Non-judicious use of this inorganic fertilizer however acidifies the soils and pollutes the environment. Integrated soil fertility management （ISFM） which involves the combined use of organic and inorganic fertilizer is recommended for improved crop yield and soil health. An experiment was carried out to determine the effect of enriching cattle manure with different ratios of inorganic fertilizers （OM： NPKS at ratios 1：2 and 1：4）, and rates on soil nutrient status, nitrogen uptake and yield of tea in the east of Rift Valley, Kenya. Enriching manures and organic manure up to a rate of 150 kg N/ha increased the level of P mature leaf. A higher N and K level in the mature leaf was observed when NPKS was applied at higher rates. In the soil, fertilizer rate up to 150 kg N/ha showed higher pH and K where organic manure and enriched manures were applied while NPKS treatment showed higher P content throughout the soil depths. Enriching organic manures with inorganic fertilizers increased yield significantly.     

Crop Yield and Soil Properties in the First 3 Years After Biochar Application to a Calcareous Soil

It remains unclear whether biochar applications to calcareous soils can improve soil fertility and crop yield. A long-term field experiment was established in 2009 so as to determine the effect of biochar on crop yield and soil properties in a calcareous soil. Five treatments were： 1） straw incorporation; 2） straw incorporation with inorganic fertilizer; 3）, 4） and 5） straw incorporation with inorganic fertilizer, and biochar at 30, 60, and 90 t ha-l, respectively. The annual yield of either winter wheat or summer maize was not increased significantly following biochar application, whereas the cumulative yield over the first 4 growing seasons was significantly increased. Soil pH, measured in situ, was increased by a maximum of 0.35 units after 2 yr following biochar application. After 3 yr, soil bulk density significantly decreased while soil water holding capacity increased with adding biochar of 90 t ha^-1. Alkaline hydrolysable N decreased but exchangeable K increased due to biochar addition. Olsen-P did not change compared to the treatment without biochar. The results suggested that biochar could be used in calcareous soils without yield loss or significant impacts on nutrient availability.     

Abundance and Community Composition of Ammonia-Oxidizers in Paddy Soil at Different Nitrogen Fertilizer Rates

Ammonia oxidation, the first and rate-limiting step of nitrification, is carried out by both ammonia-oxidizing bacteria （AOB） and ammonia-oxidizing archaea （AOA）. However, the relative importance of AOB and AOA to nitrification in terrestrial ecosystems is not well understood. The aim of this study was to investigate the effect of the nitrogen input amount on abundance and community composition of AOB and AOA in red paddy soil. Soil samples of 10-20 cm （root layer soil） and 0-5 cm （surface soil） depths were taken from a red paddy. Rice in the paddy was fertilized with different rates of N as urea of N1 （75 kg N ha＂ yr-1）, N2 （150 kg N ha~ yrl）, N3 （225 kg N ha1 yrl） and CK （without fertilizers） in 2009, 2010 and 2011. Abundance and community composition of ammonia oxidizers was analyzed by real-time PCR and denaturing gradient gel electrophoresis （DGGE） based on amoA （the unit A of ammonia monooxygenase） gene. Archaeal amoA copies in N3 and N2 were significantly （P〈0.05） higher than those in CK and N1 in root layer soil or in surface soil under tillering and heading stages of rice, while the enhancement in bacterial amoA gene copies with increasing of N fertilizer rates only took on in root layer soil. N availability and soil NO3--N content increased but soil NH4＋-N content didn＇t change with increasing of N fertilizer rates. Otherwise, the copy numbers of archaeal amoA gene were higher （P〈0.05） than those of bacterial amoA gene in root lary soil or in surface soil. Redundancy discriminate analysis based on DGGE bands showed that there were no obvious differs in composition of AOA or AOB communities in the field among different N fertilizer rates. Results of this study suggested that the abundance of ammonia-oxidizers had active response to N fertilizer rates and the response of AOA was more obvious than that of AOB. Similarity in the community composition of AOA or AOB among different N fertilizer rates indicate that the community composition of ammonia-oxidizers was relatively stable in the paddy soil at least in short term for three years.     

Effects of Corn Stover Incorporated in Dry Farmland on Soil Fertility

Seven years‘ field experiments on application of corn stover and/or cattle manure combined with chemical fertilizers were carried out in Shouyang Dryland Farming Experimental Station. Results showed that the increased available N in the plough layer was mainly influenced by the application of cattle manure; the available P was mainly influenced by the application of chemical fertilizer; the available K was mainly influenced by the incorporation of corn stover. The organic matter contents in the soils treated with corn stover or cattle manure were kept in balance under the experimental conditions. Corn yield and water use efficiency were influenced significantly not only by fertilizer N but also by incorporated corn stover. The results suggested that the highest N uptake, yield and water use efficiency could be obtained at rates of 105 kg fertilizer N, 6000 kg corn stover, and 1500 kg cattle manure per hectare. The experiments supplied information on nutrient recycling and use of corn stover as sources of fodder and organic fertilizer for balancing application of organic and inorganic fertilizer, improving soil fertility and increasing crop yield with incorporation of corn stover in soil.     

Effects of Magnesium Compound with Fertilizer on Daylily (Hemerocallis citrina Baroni) Growth and Soil Nutrients

Effects of two kinds of magnesium compound with fertilizer on Daylily (Hemerocallis citrina Baroni) growth, yield, and soil nutrients in red soil were studied. The results indicated that significant effects of magnesium applied to soils were observed in increasing Daylily (Hemerocallis citrina Baroni) yield, improving its growth, and strengthening its antivirus property as well as increasing the amount of exchangeable Mg, N, P, and K in red soil. In particular, the effects of magnesium compound fertilizer Ⅱ (MCF2) with higher Mg content were better than that of the others, which increased Daylily (Hemerocallis citrina Baroni) yield by 57.4, 32.8, and 14.5% compared to that of control treatment (CK), chemical fertilizer with nitrogen, phosphorus, potassium treatment (CF), and magnesium compound fertilizer Ⅰ treatment (MCF1) with lower Mg content. It increased soil Alkali N, available P, exchangeable K, and exchangeable Mg by 94.9, 46.5, 31.1,and 35.3%, respectively, compared with that of CK treatment. Therefore, the application of magnesium compound with fertilizer is an optimum method for improving red soil quality.     

含镁复合肥对黄花菜生长及土壤养分含量的影响

 【目的】探讨红壤旱地、特别是低肥力红壤旱地中镁对作物生长及产量的影响，为镁肥的合理施用和含镁复合肥的研制奠定进一步的基础。【方法】利用田间试验方法，研究了两种不同镁含量的复合肥对黄花菜生长、产量及红壤旱地养分含量的影响，并对其生长过程中土壤养分、作物生长等的变化进行了系统观测。【结果】两种含镁复合肥对促进黄花菜生长发育、提高黄花菜产量和抗病能力均具有良好效果，其中含镁量较高的镁肥II增产效果更优，比不施肥处理增产57.4%，比施氮磷钾处理增产32.8%，比含镁较低的镁肥I增产14.5%。两种含镁复合肥对土壤交换性镁和氮磷钾含量亦具有一定影响。其中施用镁肥II处理土壤碱解氮、速效磷、交换性钾及交换性镁含量分别比对照提高94.9%、46.5%、31.1%和35.3%。施用含镁复合肥可以明显提高黄花菜的产量、改善土壤养分状况。【结论】在红壤旱地土壤、气候和生产力水平等条件下，为保证作物优质、高产，在现有施肥结构的基础上，应考虑施用镁肥。     

不同镁肥种类在烤烟上的施用效应研究

选用4种常用镁肥品种进行实验室土壤培育试验,并在烤烟上进行镁肥施用效应的盆栽试验。结果表明,不同镁肥施入土壤后,土壤交换性镁含量显著提高。在土壤培育的第50d,各处理的土壤交换性镁含量达到最大值,在土壤培育至第90d降至最小值,各处理的土壤交换性镁含量大小顺序是硫酸镁>MgO>白云石粉>钙镁磷肥。不施镁肥的对照处理的土壤交换性镁含量在整个培育期间都最低。不同镁肥品种对烤烟的生长发育、化学成分、产量有不同的影响。在等量镁的情况下,各处理中以MgO处理的长势最好,烤烟镁含量和吸收量以及叶绿素的含量最高;总生物量和烟叶产量也最高。     

钙镁磷肥对元胡种植区酸化土壤改良效果的探究

为了探究钙镁磷肥对元胡种植区土壤酸化的阻控作用,通过连续两年的钙镁磷肥田间定位试验,以上元观镇当地元胡种植户施肥习惯为对照(CK),研究分析了在氮、钾肥用量相同的情况下,施用钙、镁、磷肥750 kg/hm~2、1 500 kg/hm~2和2 250 kg/hm~2,对土壤pH、交换性酸、阳离子交换量(CEC)、交换性盐基离子以及土壤基本肥力水平的影响。通过测算投入、产出效益,结果表明：施用钙镁磷肥能显著提升土壤pH水平,较(CK)处理提升0.27～0.31个单位,T100、T150两个处理能显著降低土壤交换性酸总量和交换性氢含量,对降低交换性铝有一定作用。施用钙镁磷肥较(CK)处理能显著提升阳离子交换量(CEC)以及交换性钙和交换性镁,是阻控土壤酸化的主要作用机制。但当施用量达到2 250 kg/hm~2时,种植元胡的新增纯收益会有所下降,伴随产生土壤中磷素过量的问题,会有造成磷素流失产生农业面源污染的风险。因此在汉中元胡种植区土壤酸化改良中推荐钙镁磷肥施用量750～1 500 kg/hm~2。     

碱性含腐植酸营养液对樱桃番茄产质量影响及其改土效果

【目的】研究碱性含腐植酸营养液施用对海南樱桃番茄地酸化土壤理化环境及植株生长、果实产量和营养品质的影响,以期为碱性含腐植酸营养液在酸化土壤改良和优质樱桃番茄生产中的应用提供参考依据。【方法】采用盆栽试验,以酸性土壤为试验土壤,设不追肥（CK）、追施0.30‰复合肥（0.30‰ CF）、0.30‰腐植酸营养液（0.30‰FDG）、0.20‰腐植酸营养液（0.20‰ FDG）和0.16‰腐植酸营养液（0.16‰ FDG）共5个处理,于樱桃番茄生育期内定期测定盆栽土壤pH,收获期（植株移栽120 d）测定叶片SPAD值、植株株高和茎粗以及果实产量和品质,测定盆栽土壤电导率、有效养分、阳离子交换性能及酶活性等指标,并对樱桃番茄果实品质、产量与土壤理化性质进行相关分析。【结果】在樱桃番茄植株移栽120 d时,施用0.20‰~0.30‰腐植酸营养液的盆栽土壤pH>5.60,而施用复合肥的土壤pH<5.00;0.20‰~0.30‰腐植酸营养液处理的盆栽土壤有机质含量相比复合肥处理均提高6.8%;腐植酸营养液处理的盆栽土壤电导率均低于复合肥处理,而阳离子交换量、交换性钙和交换性镁含量、酸性磷酸酶、蔗糖酶和多酚氧化酶活性高于复合肥处理。虽然腐植酸营养液处理的土壤有效氮磷钾含量呈现不同程度降低,但根据耕层土壤有效养分含量分级指标,其仍处于高水平,可满足樱桃番茄生长对土壤养分的需求。施用0.20‰~0.30‰腐植酸营养液的樱桃番茄植株株高、茎粗和生物量高于其他处理,果实产量和营养品质优于或等同于复合肥处理,其中0.30‰腐植酸营养液处理的果实产量较复合肥处理增产2.2%。相关分析结果表明,果实产量与土壤有机质含量、碱解氮含量和阳离子交换量呈显著（P<0.05,下同）或极显著（P<0.01,下同）正相关;品质大部分指标与土壤pH、交换性钙含量、酸性磷酸酶和蔗糖酶活性呈显著或极显著正相关,与土壤电导率呈显著负相关。【结论】腐植酸营养液处理以0.20‰~0.30‰施用量效果最佳,既能改良酸化土壤,又可提高樱桃番茄产质量。     

施加种植专用肥对甘肃西和半夏连作障碍的影响研究

[目的]研究种植专用肥对半夏连作土壤肥力、微生物多样性,半夏产量及品质的影响,为缓解半夏连作障碍提供科学施肥依据。[方法]通过大田试验,以传统复合肥料为对照(CK),设定了3个种植专用肥施肥量水平,探究处理组1(2.25 t/hm²)、处理组2(3.00 t/hm²)和处理组3(3.75 t/hm²)对土壤肥力、pH及微生物生态、半夏的农艺性状指标、产量及品质的影响。[结果]对照组半夏的株高和茎粗低于处理组、倒苗率高于处理组;种植专用肥提高了半夏的产量及水溶性浸出物,其中处理组2最为显著;种植专用肥能够改善半夏连作土壤微生物多样性,提高土壤肥力,从而提高半夏产量。[结论]中药材种植专用肥可作为一种防治措施,缓解半夏连作障碍。     

钙镁比调控对烟叶产量、化学品质及镁吸收的影响

通过田间小区试验,研究了施用镁肥进行土壤交换性钙镁比下调及叶面喷施镁肥对烤烟生长发育、产量、内在化学品质及镁吸收的影响。结果表明,与对照不施镁肥相比,土壤交换性钙镁比下调及叶面喷施镁肥有利于烤烟的生长、发育和农艺性状改善,有利于烟叶产量、产值的提高,能提升中部烟叶化学品质,土壤交换性钙镁比调控到10时最佳,其次是调控到8时,叶面喷施效果也较好;同时,与对照相比,土壤交换性钙镁比下调及叶面喷施镁肥显著提高了烟叶镁的含量及其对镁的累积量,尤其是上、中部烟叶,而且随着镁肥施用量增加和钙镁比下调,烟叶对镁的累积量显著增加。     

不同肥料配比对糜子产量和品质的调控效应

为探明不同施肥方式对糜子营养品质、食味品质和产量的影响，于2019年在山西河曲进行试验，以河曲大红糜子为材料，选用不同配比的有机肥（羊粪）、生物菌肥、尿素和复合肥，研究不同施肥配比对糜子品质和产量的影响。结果表明：不同肥料配比对糜子产量和品质性状显著影响，复合肥和有机肥（F+Y）配施显著提高糜子籽粒产量（GY）、净光合速率（P_n）、钙（Ca）和铁（Fe）含量，显著减低直链淀粉含量（AC）；相关性分析发现，籽粒产量（GY）和净光合速率（P_n）呈极显著正相关，相关系数为0.82，镁（Mg）与铁（Fe）呈极显著正相关，值为0.68，直链淀粉含量（AC）与醇溶蛋白含量（Gli）、钙（Ca）达到极显著负相关，值分别为-0.66和 -0.50；主成分分析发现，糜子各性状指标分为4个主成分，分别代表糜子食味品质、营养品质、产量指标和蛋白营养品质，综合得分以复合肥和有机肥（F+Y）处理最高，并显著高于其他处理。综上所述，复合肥（187.5 kg·hm^-2）与有机肥（1.5×10 kg·hm^-2）配施是糜子获得优质高产的主要施肥方式。     

翻压紫云英条件下化肥配施生物炭基肥对水稻Cu吸收转运的影响

针对稻田土壤重金属Cu污染问题,在翻压紫云英条件下,探究化肥与生物炭基肥配施对土壤-水稻系统Cu吸收及转运的影响。采用盆栽试验,设置5个施肥处理:对照(CK,不施肥)、常规施氮(CN)、紫云英+氮肥(CNG)、紫云英+有机肥+氮肥(CNGO)、紫云英+生物炭基肥+氮肥(CNGC)。研究了不同施肥处理对早稻五优156生长和重金属Cu吸收特性的影响。结果表明:与CN相比,CNG在无污染和污染土壤中水稻籽粒产量分别提高47.1%和50.1%;与CNG相比,CNGC在无污染和污染土壤中水稻籽粒产量分别提高4.5%和12.8%。单施化肥条件下水稻植株体中Cu的总吸收量最大,且水稻根部Cu含量最高;在污染土壤中,CNG处理下水稻糙米存在一定的重金属污染风险,而在CNGC处理下糙米中Cu含量低于相关食品卫生标准(≤10.0 mg·kg~(-1))。进一步研究表明,翻压紫云英能提高Cu从根向秸秆的转运能力,而在污染土壤条件下Cu从秸秆向谷壳的转运能力会受到抑制。在污染土壤中CN处理下Cu有效态含量最高,CNGC处理比CN处理土壤Cu有效态含量降低39.4%,比CK处理降低17.6%。研究表明,翻压紫云英条件下化肥配施生物炭基肥可以提高水稻产量,抑制水稻对Cu的吸收和转运,降低水稻籽粒中Cu含量,适宜在重金属Cu污染稻田施用。     

水稻镁肥肥效及土壤镁肥力的丰缺指标

在一定土壤交换性镁含量的范围内(土培试验结果为19-86 ppm Mg,田间试验结果为15-49 ppm Mg)。水稻施用镁肥均有一定增产效果,土壤交换性镁含量越低,增产效果越显著.土壤交换性 K/Mg 比值与水稻镁肥肥效有密切相关.在镁素不足的情况下,施用适量镁肥能提高稻谷的糙米率和精米率以及米的蛋白质、总淀粉和直链淀粉含量.不同水稻品种对培养液镁浓度要求不同,其要求高低顺序为:四优30>(杂交稻)>金晚6号(常规稻)>黎明和南56(粳稻).红壤性土壤交换性镁含量与水稻相对产量和镁吸收量相关最密切,确定以1mol/l 中性醋酸铵淋洗测定的土壤交换性镁含量来划分土壤镁肥力丰缺指标.对水稻而言,红壤性水稻土交换性镁小于6 ppm 为低量,6—26 ppm 为中量,大于26 ppm 为高量.