Effects of Super Absorbent Polymers on Yield and Water-saving and Drought-escaping Mechanism in Spring Maize

The effects of super absorbent polymers （SAP） on yield as well as water-saving and drought-escaping mechanism in spring maize in the seasonal drought region were studied. As shown by the results, during the seasonal drought in southern China, SAP treatment promoted the soil moisture, improved the capability of absorption and transportation of roots, promoted physiological and biochemical functions, increased the chlorophyll content, photosynthetic rate and intercellular CO2 concentration, and reduced the stomatal conductance and transplre.tion rate. As a result, the economic characters of spring maize were improved, and the yield was increased.

Influences of Nitrogen Level on Carbon Metabolism of Spring Maize

[Objective]To study the effect of supplies of nitrogen level on spring maize leaf blade carbon metabolism.[Method]In this experiment,field trail and biochemistry analysis were used to study the effect of the diference-nitrogen level on the content of chlorophyl and carboxylase activity of RuBP and PEP in the leaf of spring maize during main growing period.[Result]Applying proper amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize,insufficient or excessive（N 400 kg/hm^2） of nitrogenous fertilizer has the adverse effect.[Conclusion]In this experiment,applying 300 kg/hm^2 amount of N could keep relative higher content of chlorophyl and higher activity of carboxylase of RuBP and PEP in the leaf of spring maize during main growing period.It was important to strengthens the leaf blade photosynthesis ability,promote the yield formation and postpone the decline of leaf blade.

Effects of Different Nitrogen Application Methods on Enzyme Activities in Leaves at Late Growth Stage of Spring Maize

[Objective] This paper aimed at exploring the effects of different nitrogen application methods on the enzyme activities of leaves at ear position in late growth stage of maize. [Method] By pot experiment, the superoxide dismutase （SOD） activity, peroxidase （POD） activity, malonyl dialdehyde （MDA） content and soluble protein content were determined. [Result] At the filling stage and ripening stage, with the increasing of nitrogen application rate, MDA content gradually decreased, while SOD activity, POD activity and soluble protein content increased. MDA content with two topdressing nitrogen was lower than that with one top dressing nitrogen at the same nitrogen application rate, while SOD activity, POD activity and soluble protein content with two topdressing nitrogen were higher than that with one topdressing nitrogen. [Conclusion] Different nitrogen application methods have relatively significant effects on the MDA content, SOD activity, POD activity and soluble protein content, which is of certain directive significance for preventing spring maize prematuration.

Application Effects of Ultra-fine Powder Shaped Maize Seed Coating Agent in Spring Sowing areas in northeast China

The research explored adaptability maize seed coating agent in spring sowing and effects of ultra-fine powder shaped areas in northeast China. The results showed that germination potential and rate both improved around 5% and the num- ber of root increased by 4% in the treatments with ultra-fine powder shaped maize seed coating agent compared with the control group without seed coating. What＇s more, the treatments with ultra-fine powder shaped maize seed coating agent took advantages in terms of fresh weight of seeding, stem diameter, and dry weight. It is notable that control effects on underground insects performed the best, with per- centage over 94%, which is more excellent relative to other agents in markets. Therefore, ultra-fine powder shaped maize seed coating agent can be widely applied in spring sowing areas in northeast China, without side effects.

Study on Matter Production and Population Photosynthetic Characteristics of High-yielding Spring Maize under Different Modes

In order to construct a good population structure, improve the light energy utilization ratio, and give a full play to the high-yielding potential of spring maize, the effects of maize variety, planting density and fertilizer management on matter production and population photosynthetic physiological indices of spring maize were investigated under three different modes （traditional mode, optimized mode and high- yielding mode）. The results showed that compared with those under the traditional mode, the yield of spring maize under the optimized mode and high-yielding mode was increased by 10.79% and 27.62%, respectively, and the barren tip length was reduced significantly. Among the three modes, the leaf area index （LA/）, leaf area duration （LAD）, dry matter accumulation （DMA） and crop growth rate （CGR） all ranked as high-yielding rnode＇s〉optimized mode＇s〉traditional mode＇s. In conclusion, optimized variety, appropriately increased planting density and strengthened fertilizer management are the key measures to obtain high yield of spring maize.

基于留一交叉验证法的APSIM-Maize产量模拟

作物生长模型APSIM广泛应用于作物估产和农业生产管理中,在观测数据有限的情况下,开展留一交叉验证是提高模型模拟能力的关键途径。本研究以内蒙古十大孔兑地区春玉米为研究对象,量化分析了APSIM-Maize模型模拟2012—2019年间玉米产量对关键参数的敏感性,并根据参数敏感性强弱对APSIM-Maize模型进行交叉验证与参数率定,提高了模型模拟能力。主要结果为:(1)影响春玉米产量的敏感性参数由强到弱依次是:蒸腾效率系数、辐射利用效率、开花到成熟的积温、出苗到拔节的积温、开花到灌浆的积温、潜在灌浆速率、光周期和最大穗粒数;(2)交叉验证时,APSIM-Maize模型各参数变异系数在1.06%~23.32%之间波动,总体上模型参数变异性小,可靠性高;(3)APSIM-Maize模型经过参数率定后的模拟产量与实测产量具有较好的一致性(R^(2)=0.72,RMSE=401.5kg hm^(-2)),模型在十大孔兑地区春玉米产量的评估中表现出较好的适应性。本研究为在农田试验数据有限情况下提高模型率定参数的可靠性提供了新的研究思路和科学依据。

Effect of subsoil tillage depth on nutrient accumulation, root distribution, and grain yield in spring maize

A four-year field experiment was conducted to investigate the effect of subsoiling depth on root morphology, nitrogen(N), phosphorus(P), and potassium(K) uptake, and grain yield of spring maize. The results indicated that subsoil tillage promoted root development,increased nutrient accumulation, and increased yield. Compared with conventional soil management(CK), root length, root surface area, and root dry weight at 0–80 cm soil depth under subsoil tillage to 30 cm(T1) and subsoil tillage to 50 cm(T2) were significantly increased, especially the proportions of roots in deeper soil. Root length, surface area, and dry weight differed significantly among three treatments in the order of T2 > T1 > CK at the12-leaf and early filling stages. The range of variation of root diameter in different soil layers in T2 treatment was the smallest, suggesting that roots were more likely to grow downwards with deeper subsoil tillage in soil. The accumulation of N, P, and K in subsoil tillage treatment was significantly increased, but the proportions of kernel and straw were different. In a comparison of T1 with T2, the grain accumulated more N and P, while K accumulation in kernel and straw varied in different years. Grain yield and biomass were increased by 12.8% and 14.6% on average in subsoil tillage treatments compared to conventional soil treatment. Although no significant differences between different subsoil tillage depths were observed for nutrient accumulation and grain yield, lodging resistance of plants was significantly improved in subsoil tillage to 50 cm, a characteristic that favors a high and stable yield under extreme environments.

Tillage and straw mulching impacts on grain yield and water use efficiency of spring maize in Northern Huang–Huai–Hai Valley

A two-year field experiment(2012–2013) was conducted to investigate the effects of two tillage methods and five maize straw mulching patterns on the yield, water consumption,and water use efficiency(WUE) of spring maize(Zea mays L.) in the northern Huang–Huai–Hai valley of China. Compared to rotary tillage, subsoil tillage resulted in decreases in water consumption by 6.3–7.8% and increases in maize yield by 644.5–673.9 kg ha-1, soil water content by 2.9–3.0%, and WUE by 12.7–15.2%. Chopped straw mulching led to higher yield,soil water content, and WUE as well as lower water consumption than prostrate whole straw mulching. Mulching with 50% chopped straw had the largest positive effects on maize yield, soil water content, and WUE among the five mulching treatments. Tillage had greater influence on maize yield than straw mulching, whereas straw mulching had greater influence on soil water content, water consumption, and WUE than tillage. These results suggest that 50% chopped straw mulching with subsoil tillage is beneficial in spring maize production aiming at high yield and high WUE in the Huang–Huai–Hai valley.

Basic Soil Productivity of Spring Maize in Black Soil Under Long-Term Fertilization Based on DSSAT Model

Increasing basic farmland soil productivity has significance in reducing fertilizer application and maintaining high yield of crops. In this study, we defined that the basic soil productivity （BSP） is the production capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local environment and field management. Based on 22-yr （1990-2011） long-term experimental data on black soil （Typic hapludoll） in Gongzhuling, Jilin Province, Northeast China, the decision support system for an agro-technology transfer （DSSAT）-CERES-Maize model was applied to simulate the yield by BSP of spring maize （Zea mays L.） to examine the effects of long-term fertilization on changes of BSP and explore the mechanisms of BSP increasing. Five treatments were examined： （1） no-fertilization control （control）; （2） chemical nitrogen, phosphorus, and potassium （NPK）; （3） NPK plus farmyard manure （NPKM）; （4） 1.5 time of NPKM （1.5NPKM） and （5） NPK plus straw （NPKS）. Results showed that after 22-yr fertilization, the yield by BSP of spring maize significantly increased 78.0, 101.2, and 69.4% under the NPKM, 1.5NPKM and NPKS, respectively, compared to the initial value （in 1992）, but not significant under NPK （26.9% increase） and the control （8.9% decrease）. The contribution percentage of BSP showed a significant rising trend （P〈0.05） under 1.5NPKM. The average contribution percentage of BSP among fertilizations ranged from 74.4 to 84.7%, and ranked as 1.5NPKM〉NPKM〉NPK〉NPKS, indicating that organic manure combined with chemical fertilizers （I.5NPKM and NPKM） could more effectively increase BSP compared with the inorganic fertilizer application alone （NPK） in the black soil. This study showed that soil organic matter （SOM） was the key factor among various fertility factors that could affect BSP in the black soil, and total N, total P and/or available P also played important role in BSP increasing. Compared with the chemical fertilization, a balanced chemical plus manure or straw fertilization （NPKM or NPKS） not only increased the concentrations of soil nutrient, but also improved the soil physical properties, and structure and diversity of soil microbial population, resulting in an iincrease of BSP. We recommend that a balanced chemical plus manure or straw fertilization （NPKM or NPKS） should be the fertilization practices to enhance spring maize yield and improve BSP in the black soil of Northeast China.

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.

The causes and impacts for heat stress in spring maize during grain filling in the North China Plain--A review

High-temperature stress （HTS） at the grain-filling stage in spring maize （Zea mays L.） is the main obstacle to increasing productivity in the North China Plain （NCP）. To solve this problem, the physiological mechanisms of HTS, and its causes and impacts, must be understood. The HTS threshold of the duration and rate in grain filling, photosynthetic characteristics （e.g., the thermal stability of thylakoid membrane, chlorophyll and electron transfer, photosynthetic carbon assimilation）, water status （e.g., leaf water potential, turgor and leaf relative water content） and signal transduction in maize are reviewed. The HTS threshold for spring maize is highly desirable to be appraised to prevent damages by unfavorable temperatures during grain filling in this region. HTS has negative impacts on maize photosynthesis by damaging the stability of the thylakoid membrane structure and degrading chlorophyll, which reduces light energy absorption, transfer and photosynthetic carbon assimilation. In addition, photosynthesis can be deleteriously affected due to inhibited root growth under HTS in which plants decrease their water-absorbing capacity, leaf water potential, turgor, leaf relative water content, and stomatal conductance. Inhibited photosynthesis decrease the supply of photosynthates to the grain, leading to falling of kernel weight and even grain yield. However, maize does not respond passively to HTS. The plant transduces the abscisic acid （ABA） signal to express heat shock proteins （HSPs）, which are molecular chaperones that participate in protein refolding and degradation caused by HTS. HSPs stabilize target protein configurations and indirectly improve thylakoid membrane structure stability, light energy absorption and passing, electron transport, and fixed carbon assimilation, leading to improved photosynthesis. ABA also induces stomatal closure to maintain a good water status for photosynthesis. Based on understanding of such mechanisms, strategies for alleviating HTS at the grain-filling stage in spring maize are summarized. Eight strategies have the potential to improve the ability of spring maize to avoid or tolerate HTS in this study, e.g., adjusting sowing date to avoid HTS, breeding heat-tolerance varieties, and tillage methods, optimizing irrigation, heat acclimation, regulating chemicals, nutritional management, and planting geometric design to tolerate HTS. Based on the single technology breakthrough, a com- prehensive integrated technical system is needed to improve heat tolerance and increase the spring maize yield in the NCP.

A preliminary study of the effects of plastic film-mulched raised beds on soil temperature and crop performance of early-sown short-season spring maize(Zea mays L.) in the North China Plain

To identify a strategy for earlier sowing and harvesting of spring maize(Zea mays L.) in an alternative maize–maize double cropping system, a 2-year field experiment was performed at Quzhou experimental station of China Agricultural University in 2014 and 2015. A short-season cultivar, Demeiya number 1(KX7349), was used in the experiment. Soil temperature to 5 cm depth in the early crop growth stage, crop growth, crop yield, and water use of different treatments(plastic film-mulched raised bed(RF) and flat field without plastic film mulching(CK) in 2014; RF, plastic film-mulched flat field(FF), and CK in 2015)were measured or calculated and compared. Soil temperature in the film-mulched treatments was consistently higher than that in CK(1.6–3.5 °C in average) during the early growth stage. Crops in plastic film-mulched treatments used 214 fewer growing-degree days(GDDs) in 2014 and 262 fewer GDDs in 2015. In 2014, the RF treatment yielded 32.7%higher biomass than CK, although its 9.4% higher grain yield was not statistically significant. Also, RF used 17.9% less water and showed 33.1% higher water use efficiency(WUE) than CK. In 2015, RF and FF showed 56.2% and 49.5% higher yield, 15.0% and 4.5%lower water use(ET), and 63.4% and 75.7% higher WUE, respectively, than CK. RF markedly increased soil temperature in the early crop season, accelerated crop growth, reduced ET,and greatly increased crop yield and WUE. Compared with FF, RF had no obvious effect on crop growth rate, although soil temperature during the period between sowing and stem elongation was slightly increased. However, RF resulted in lower ET and higher WUE than FF. Effects of RF on soil water dynamics as well as its cost-effectiveness remain topics for further study.

Impacts of Fertilization Alternatives and Crop Straw Incorporation on N_2O Emissions from a Spring Maize Field in Northeastern China

Spring maize is one of the most popular crops planted in northeastem China. The cropping systems involving spring maize have been maintaining high production through intensive management practices. However, the high rates of nitrogen （N） fertilizers application could have introduced a great amount of nitrous oxide （N2O） into the atmosphere. It is crucial for sustaining the maize production systems to reduce N2O emissions meanwhile maintaining the optimum yields by adopting alternative farming management practices. The goal of this study was to evaluate effects of alternative fertilization and crop residue management practices on N2O emission as well as crop yield for a typical maize field in northeastern China. Field experiments were conducted during the 2010-2011 maize growing seasons （from early May to late September） in Liaoning Province, northeastern China. N2O fluxes were measured at the field plots with six different treatments including no N fertilizer use （CK）, farmers＇ conventional N fertilizer application rate （FP）, reduced N fertilizer rate （OPT）, reduced N fertilizer rate combined with crop straw amendment （OPTS）, slow-release N fertilizer （CRF）, and reduced N fertilizer rate combined with nitrification inhibitor （OPT＋DCD）. The static chamber method combined with gas chromatography technique was employed to conduct the measurements of N2O fluxes. The field data showed that N2O emissions varied across the treatments. During the maize growing season in 2010, the total N2O emissions under the treatments of CK, FP, OPT, OPTS, and CRF were 0.63, 1.11, 1.03, 1.26, and 0.98 kg N ha-1, respectively. The seasonal cumulative N2O emissions were 0.54, 1.07, 0.96, 1.12, and 0.84 kg N ha1, respectively, under CK, FP, OPT, OPTS, and OPT＋DCD in 2011. In comparison with FP, CRF or OPT＋DCD reduced the N2O emissions by 12 or 21%, respectively, while the crop yields remained unchanged. The results indicate that the reduction of N-fertilizer application rate in combination with the slow-release fertilizer type or nitrification inhibitor could effectively mitigate N2O emissions from the tested field. The incorporation of crop residue didn＇t show positive effect on mitigating N2O emissions from the tested cropping system. The field study can provide useful information for the on-going debate on alternative N fertilization strategies and crop straw management in China. However, further studies would be needed to explore the long-term impacts of the alternative management practices on a wide range of environmental services.

Estimates of N_2O Emissions and Mitigation Potential from a Spring Maize Field Based on DNDC Model

Agricultural production plays an important role in affecting atmospheric nitrous oxide （N20） concentrations. Field measurements were conducted in Dalian City, Liaoning Province in Northeast China from two consecutive years （2009 and 2010） to estimate NzO emissions from a spring maize field, a main cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, DeNitrification-DeComposition （DNDC）, for its applicability for the cropping system. The validated DNDC was then used for exploring strategies to reduce N20 emissions from the target field. The results showed that the major N20 pulse emissions occurred with duration of about 3-5 d after fertilizer application in both years 2009 and 2010, which on average accounted for about 60% of the total N20 emissions each year. Rainfall and fertilizer application were the major factors influencing the N20 emissions from spring maize field. The average N20 flUXeS from the CK （control plot, without fertilization） and FP （traditional chemical N fertilizer） treatments were 23.1 and 60.6 gg m-2 h-~ in 2009, respectively, and 21.5 and 64.3 gg m-2 h-~ in 2010, respectively. The emission factors （EFs） of the applied N fertilizer （270 kg N ha-1） as N20- N were 0.62% in 2009 and 0.77% in 2010, respectively. The comparison of modeled daily NzO emission fluxes against observations indicated that the DNDC model had a good performance even if without adjusting the internal parameters. The modeled results showed that management practices such as no-till, changing timing or rate of fertilizer application, increasing residue incorporation, and other technically applicable measures could effectively reduce N20 emissions from the tested fields. Our study indicated that avoiding application of N fertilizers at heavy rainfall events or splitting the fertilizer into more applications would be the most feasible approaches to reduce N20 emissions from spring maize production in Northeast China.

Water Requirements and Irrigation Scheduling of Spring Maize Using GIS and CropWat Model in Beijing-Tianjin-Hebei Region

Due to the over use of available water resources, it has become very important to define appropriate strategies for planning and management of irrigated farmland. In this paper, Beijing-Tianjin-Hebei (Jing-Jin-Ji) region was chosen as the case study area for its special political and economic status and its severe water problem. To achieve effective planning, the information about crop water requirements, irrigation withdrawals, soil types and climatic conditions were obtained in the study area. In the meantime, a GIS method was adopted, which extends the capabilities of the crop models to a regional level. The main objectives of the study are: 1) to estimate the spatial distribution of the evapotranspiration of spring maize; 2) to estimate climatic water deficit; 3) to estimate the yield reduction of spring maize under different rainfed and irrigated conditions. Based on the water deficit analysis, recommended supplemental irrigation schedule was developed using CropWat model. Compared to the rainfed control, the two or three times of supplemental water irrigated to spring maize at the right time reduced the loss of yield, under different scenarios.

Differences of yield and nitrogen use efficiency under different applications of slow release fertilizer in spring maize

Excessive or insufficient application of fertilizer has raised broader concerns regarding soil and environmental degradation.One-time application of slow release fertilizer (SF) has been widely used to reduce yield gap with potential maize yield and improve nitrogen use efficiency (NUE).A 2-year field experiment (2018–2019) was conducted to evaluate the effects of SF rates from 0 to 405 kg N ha^(–1) (named F0,SF225,SF270,SF315,SF360,and SF405) and 405 kg N ha^(–1) of common fertilizer(CF405) on the grain yield,biomass and N accumulation,enzymatic activities related with carbon–nitrogen metabolism,NUE and economic analysis.Results indicated that the highest grain yields,NUEs and economic returns were achieved at SF360in both varieties.The enzymatic activities related with carbon–nitrogen metabolism,pre-and post-silking accumulation of biomass and N increased with increasing SF rate,and they were the highest at SF360 and SF405.The grain yield at SF360had no significant difference with that at SF405.However,the N partial factor productivity,N agronomic efficiency and N recovery efficiency at SF360 were 9.8,6.6 and 8.9% higher than that at SF405.The results also indicated that the average grain yields,NUE and economic benefit at SF405 were 5.2,12.3 and 18.1% higher than that at CF405.In conclusion,decreasing N rate from 405 kg ha^(–1)(CF) to 360 kg ha^(–1)(SF) could effectively reduce the yield gap between realized and potential maize yields.The N decreased by 11.1%,but the yield,NUE and economic benefit increased by 3.2,22.2 and 17.5%,which created a simple,efficient and business-friendly system for spring maize production in Jiangsu Province,China.

Effect of Limited Single Irrigation on Yield of Winter Wheat and Spring Maize Relay Intercropping

A field experiment was conducted during the 2002/2003 cropping season of winter wheat （Triticum aestivum） and spring maize （Zea mays） to evaluate the effect of limited single drip irrigation on the yield and water use of both crops under relay intercropping in a semi-arid area of northwestern China. A controlled 35 mm single irrigation, either early or late, was applied to each crop at a certain growth stage. Soil water, leaf area, final grain yield and yield components such as the thousand-grain weight, length of spike, fertile spikelet number, number of grains per spike, and grain weight per spike were measured, and water use efficiency and leaf area index were calculated for the irrigated and non-irrigated relay intercropping treatments and sole cropping controls. The results showed that yield, yield components, water use efficiency, and leaf area index in the relay intercropping treatments were affected by limited single drip irrigation during various growth stages of wheat and maize. The total yields in the relay intercropping treatment irrigated during the heading stage of wheat and the heading and anthesis stage of maize were the highest among all the treatments, followed by that irrigated during the anthesis stage of wheat and silking stage of maize; so was the water use efficiency. Significant differences occurred in most yield components between the irrigated and non-irrigated relay-intercropping treatments. The dynamics of the leaf area index in the relay-intercropped or solely cropped wheat and maize showed a type of single-peak pattern, whereas that of the relay intercropping treatments showed a type of double-peak pattern. Appropriately, limited single irrigation and controlled soil water content level could result in higher total yield, water use efficiency, and leaf area index, and improved yield components in relay intercropping. This practice saved the amount of water used for irrigation and also increased the yield. Therefore, heading stage of wheat and heading and anthesis stage of maize were suggested to be the optimum limited single irrigation time for relay-intercropped wheat and maize in the semi-arid area.

The Effect of Organo-Mineral Fertilizer Applications on the Yield of Winter Wheat, Spring Barley, Forage Maize and Grass Cut for Silage

Biosolids were applied with urea to produce a granulated organo-mineral fertiliser (OMF) for application by farm fertiliser equipment to a range of agricultural crops. The recommended rates of nitrogen, phosphate and potash were calculated for the test crops using “The Fertiliser Manual”, which assesses the nutrient requirement based on previous cropping, rainfall and soil index. The OMF produced similar crop yields compared to ammonium nitrate fertiliser when applied as a top-dressing to winter wheat, forage maize and grass cut for silage in the cropping years 2010 to 2014. In 2012 the grain yield of spring barley top-dressed with OMF was significantly lower than the conventional fertiliser treatment, due to dry conditions following application. For this reason it is recommended that OMF is incorporated into the seedbed for spring sown crops and The Safe Sludge Matrix guidelines followed. The experimental work presented shows that OMF can be used in sustainable crop production systems as a source of nitrogen and phosphorus for a range of agricultural crops.

Study on the Photosynthetic Characteristics in Spring Maize (Zea mays L.)of Different Quality Type

common maize synthetic rate（ Photosynthetic characteristics were probed by sweet maize, waxy maize, high starch maize and The results revealed that leaf area index （LAI）, chlorophyll a content, chlorophyll b content,photo-PR） showed single peak curve at the whole growth stage. The stages of peak were different according to different varieties. NEAUS4 had the lowest peak and while SIDAN 19 had the highest among all stages. Ratio of chlorophyll a to b was low at seedling stage, reached the peak atjointing stage and then declined. SIDAN 19 had the lower level at the last stages.

Delaying application time of slow-release fertilizer increases soil rhizosphere nitrogen content,root activity,and grain yield of spring maize

Application of slow-release fertilizer(SF)is a nutrient-management measure aimed at improving maize nutrient use and yield and saving labor cost.One-time application of SF at sowing usually results in nutrient deficiency during the post-silking stage,owing to the long growth period of spring maize.This study was conducted to investigate the effects on spring maize of SF application stage(zero,three-,and six-leaf stages,designated as SF0,SF3,and SF6,respectively)on grain yield,total soil rhizosphere nitrogen(N)content,and root activity,in comparison with the conventional fertilization mode(CF,application of compound fertilizer at sowing time,and topdressing urea at six-leaf and tasseling stages)at the same fertilization level as the control.Compared with no fertilization(F0)and CF,SF increased grain number and weight.The maize cultivars Suyu 30(SY30)and Jiangyu 877(JY877)produced the highest grain yield and net return under SF6 treatment over the three years.SF6 increased enzymatic activities including oxidoreductase,hydrolase,transferase,and lyase in rhizosphere soil at silking(R1)and milking stages(R3).SF6 increased the total N contents of rhizosphere soil by 7.1%at R1 and 9.2%R3 stages compared with SF0.The activities of antioxidant enzymes in roots were increased under SF6 treatments at R1and R3.The mean root activities of SF0,SF3,and SF6 increased by 7.1%,12.8%,and 20.5%compared with CF at R1 and by 8.8%,13.0%,and 23.5%at R3.Delaying the application time of SF could increase grain yield by increasing total N content of rhizosphere soil,delaying root senescence,and increasing root activity at the late reproductive stage.Applying SF at the six-leaf stage is recommended as an effective fertilization strategy for the sustainable production of spring maize in southern China.