Using Automation Controller System and Simulation Program for Testing Closed Circuits of Mini-Sprinkler Irrigation System

The field experiments were conducted at the experimental farm of Faculty of agricultural, southern Illinois University SIUC, USA. The project makes the irrigation automated. With the use of low cost sensors and the simple circuitry makes currently project a low cost product, which can be bought even by a poor farmer. This research work is best suited for places where water is scares and has to be used in limited quantity and this proposal is a model to modernize the agriculture industries at a mass scale with optimum expenditure. In the field of agricultural engineering, use of sensor method of irrigation operation is important and it is well known that closed circuits of Mini-sprinkler irrigation system are very economical and efficient. Closed circuits are considered one of the modifications of Mini-sprinkler irrigation system, and added advantages to Mini-sprinkler irrigation system because it can relieve low operating pressures problem at the end of the lateral lines. In the conventional closed circuits of Mini-sprinkler irrigation system, the farmer has to keep watch on irrigation timetable, which is different for different crops. Using this system, one can save manpower, water to improve production and ultimately profit. The data could be summarized in following: Irrigation methods under study when using lateral length 60 mcould be ranked in the following ascending order according the values of the predicted and measured head losses CM1M-SIS CM2M-SIS.The correlation (Corr.) coefficients were used to compare the predicted and measured head losses along the lateral lines of all the closed circuits designs. Generally, the values of correlation analysis were (>0.90) were obtained with 0% field slope60 mlength (experimental conditions) for all closed circuits.The interaction between irrigation methods: at the start there are significant differences between CM2M-SIS and CM1M-SIS.

Effect of Cultivar, Irrigation and Nitrogen Fertilization on Chickpea (<i>Cicer arietinum</i>L.) Productivity

A 2-year field study was conducted in northern Greece to investigate the effect of nitrogen fertilization and irrigation on productivity of three Greek chickpea varieties (“Amorgos” “Serifos”, “Andros”). Chickpea, grown under irrigation regime (30 + 30 mm of water) and fertilized with 50 kg·N·ha-1 before planting and with 40 kg·N·ha-1 at blossom growth stage, produced more total dry biomass and seed yield as compared with that grown under non-irrigated conditions and fertilized with 50 kg·N·ha-1 before planting only. In particular, irrigation and nitrogen fertilization at blossom growth stage increased total dry weight of chickpea by 18.3% and 18.5%, respectively, as compared with that of non-irrigated and fertilized with N before planting. The corresponding increase of seed yield was 30.5% and 20%, respectively. The total dry biomass of “Amorgos” was 10% and 13% greater than that of “Serifos” and “Andros”, while its respective seed yield increase was 5% and 16%. Finally, the quantum yield of photosystem II of chickpea was not affected by irrigation or fertilization. These results indicated that nitrogen fertilization at blossom growth stage combined with irrigation increased seed yield of all chickpea varieties, whereas the same treatments did not have any effect on plant quantum yield of photosystem II.

Effect of Irrigation and Fertilization on Population Structure and Yield of Wheat

[Objectives] This study was conducted to investigate the effects of irrigation and fertilization on population structure and yield of wheat.[Methods]With Shannong 29 as an experimental material,the effects of irrigation and fertilization on population,dry matter accumulation and yield of wheat were studied.[Results]Integrated water-saving irrigation and fertilization of ridged field was the best with the highest population,dry matter accumulation and yield of wheat.[Conclusions]This study provides a theoretical basis for high-yield and high-efficiency wheat production with saved water and fertilizers.

Effects of Light, Fertilizer and Irrigation on Growth and Physiological Characteristics of Glehnia littoralis

The aim was to promote the cultivation and application of medicinal plants Glehnia littoralis. [Method] Glehnia littoralis was used as experi-mental materials in this study, and orthogonal design was performed to investigate the effects of light, fertilizer and irrigation on the growth of Glehnia littoralis. The biomass, leaf chlorophyl and malondialdehyde （MDA） content were determined to study its response to light, fertilizer and irrigation. [Result] The results showed that the optimum cultivation conditions of Glehnia littoralis were not completely consistent with wild living environments. Lightly shade, highly fertilization （21.38-32.08 g） and proper irrigation （500-750 ml） were suitable for artificial cultivated Glehnia littoralis. Under the condition, the biomass was enhanced, leaf chlorophyl and carotene con-tent were increased, and MDA content changed significantly. Under stress condi-tions, the biomass of Glehnia littoralis reduced, with the decrease of chlorophyl and carotenoid content. The content of chlorophyl a was more sensitive to the variation of light, fertilizer, irrigation and other environmental factors, and MDA content signifi-cantly increased by stress conditions. [Conclusion] This research can provide refer-ence for large-scale artificial cultivation of Glehnia littoralis.

Study on Liquid Special Fertilizer for Drip Irrigation of Sugarcane and Its Irrigation Mode in Guangxi Lateritic Red Soil Region

[Objective] Liquid special fertilizer for drip irrigation of sugarcane was de- veloped and the fertilizer patterns were explored in the production to provide techni- cal support for fertigation production of modern agriculture. [Method] ROC22 was selected as experimental material, two formulas of liquid special fertilizer for sugar- cane developed by the cooperation between Guangxi Academy of Agricultural Sci- ences and New Orientation （Guangxi） Chemical Industry Co.,Ltd. were selected, namely, balanced 21-21-21 ~ TE of Xinfangxiang and hyperkalemic 13-6-39-TE of Xinfangxiang. Taking conventional fertilization as the control （CK）, two modes of ap- plying base fertilizer at the earlier stage ＋ fertigation in the tillering stage and ferti- gation in the whole growth period were set. [Result] The two modes of fertilization had not significant effects on the emergence of sugarcane, but applying base fertil- izer at the earlier stage ＋ timely applying water soluble fertilizer in the tillering stage was conducive to the tillering of sugarcane. Harvest results showed that the effects of different treatments on plant height and yield were significant, in which the yield of sugarcane under the treatment of hyperkalemic water-soluble fertilizer increased by 13.04% compared with conventional treatment, and the income increased by 4 500 yuan/hm2, [Conclusion] Liquid special fertilizer for drip irrigation of sugarcane signifi- cantly promoted the growth of sugarcane, moreover, under the same condition, the effect of hyperkalemic water-soluble fertilizer was better.

Effects of Different Irrigation Times and Nitrogen Fertilizer Application on Leaf Area Index and Grain Yield of ‘Yujiao 5'

To provide ＂more reasonable, more saving and more efficient＂ water and fertilizer application proposals, taking ‘Yujiao 5＇ as the experimental material, the effects of different irrigation times and nitrogen application treatments on the leaf area index and yield of wheat were studied using three-factor split plot method. The results showed that irrigation times, nitrogen application rate and the ratio of basa to topdressed nitrogen respectively had significant effects on the leaf area index, the yield and component factors of wheat. Under the treatment of W1（irrigation before sowing）, the leaf area index showed a positive linear correlation with nitrogen application rate; under the treatments of W2（irrigation before sowing and at jointing stage） and W3（irrigation before sowing, at jointing stage and at grain filling stages）,the leaf area index showed a positive linear correlation with nitrogen application rate at the jointing stage, booting stage and heading stage; 20 d after heading, the leaf area index showed a quadric curve relationship with nitrogen application rate at these stages, and the LAI of N3R2 was the highest. Under different irrigation times,the yield, ear number and kernels per ear showed quadric curve relationship with nitrogen application rate, 1 000-seed weight showed the trend of linear decrease with the increase of nitrogen application rate. Under the treatment combination of irrigation before sowing, at jointing stage and at grain filling stage, nitrogen application rate at 240 kg/hm^2 and the ratio of basal to topdressed nitrogen of 5：5, the grain yield（8 609.60 kg/hm^2）, ear number（688.2×104/hm^2） and kernel number per ear（37.9 grains） reached the highest value at W3N3R2, and the grain yield of W3N3R2 increased by 144.8% compared to the W1N0. In conclusion, in Eastern Henan where the rainfall is insufficient at the late growth stage of wheat, the irrigation-saving space in wheat production is relatively small, but the nitrogen-saving space is relatively large.

Nitrate leaching of winter wheat grown in lysimeters as affected by fertilizers and irrigation on the North China Plain

Proper application of nitrogen（N） fertilizers and irrigation management are important production practices that can reduce nitrate leaching into groundwater and improve the N use efficiency（NUE）. A lysimeter/rain shelter facility was used to study effects of the rate of N fertilization, type of N fertilizer, and irrigation level on key aspects of winter wheat production over three growing seasons（response variables were nitrate transport, N leaching, and NUE）. Results indicated that nitrate concentration in the soil profile and N leaching increased with the rate of N fertilization. At the end of the third season, nitrate concentration in the top 0–75 cm layer of soil was higher with manure treatment while urea treatments resulted in higher concentrations in the 100–200 cm layer. With normal irrigation, 3.4 to 15.3% of N from applied fertilizer was leached from the soil, yet no leaching occurred under a stress irrigation treatment. The manure treatment experienced less N leaching than the urea treatment in all cases except for the 180 kg N ha^-1 rate in 2011–2012（season 3）. In terms of grain yield（GY）, dry matter（DM） or NUE parameters, values for the manure treatment were lower than for the urea treatment in 2009–2010（season 1）, yet were otherwise higher for urea treatment in season 3. GY and crop nitrogen uptake（NU） were elevated when the rate of N fertilizer increased, while the NUE decreased; GY, DM, and NU increased with the amount of irrigation. Data indicated that reduced rates of N fertilization combined with increased manure application and proper irrigation management can lower nitrate levels in the subsoil and reduce potential N leaching into groundwater.

Leaching and Transformation of Nitrogen Fertilizers in Soil After Application of N with Irrigation: A Soil Column Method

A soil column method was used to compare the effect of drip fertigation (the application of fertilizer through drip irrigation systems, DFI) on the leaching loss and transformation of urea-N in soil with that of surface fertilization combined with flood irrigation (SFI), and to study the leaching loss and transformation of three kinds of nitrogen fertilizers (nitrate fertilizer, ammonium fertilizer, and urea fertilizer) in two contrasting soils after the fertigation. In comparison to SFI, DFI decreased leaching loss of urea-N from the soil and increased the mineral N (NH4+-N + NO3- -N) in the soil. The N leached from a clay loam soil ranged from 5.7% to 9.6% of the total N added as fertilizer, whereas for a sandy loam soil they ranged between 16.2% and 30.4%. Leaching losses of mineral N were higher when nitrate fertilizer was used compared to urea or ammonium fertilizer. Compared to the control (without urea addition), on the first day when soils were fertigated with urea, there were increases in NH4+-N in the soils. This confirmed the rapid hydrolysis of urea in soil during fertigation. NH4+-N in soils reached a peak about 5 days after fertigation, and due to nitrification it began to decrease at day 10. After applying NH4+-N fertilizer and urea and during the incubation period, the mineral nitrogen in the soil decreased. This may be related to the occurrence of NH4+-N fixation or volatilization in the soil during the fertigation process.

Effects of drip irrigation modes on growth and physiological characteristics of Arabica coffee under different N levels

The objective of this study was to obtain the water-saving and efficient production mode of Arabica coffee. The effects of three drip irrigation modes,conventional drip irrigation( CDI),alternate drip irrigation( ADI) and fixed drip irrigation( FDI) on growth,photosynthetic characteristics,biomass accumulation and irrigation water use efficiency of Arabica coffee were investigated under three nitrogen levels,high nitrogen( NH),middle nitrogen( NM) and low nitrogen( NL). The results show that there was a significant Logistic curve between the plant height,the stem diameter of Arabica coffee and growth days. Compared with CDI,ADI had no significant effects on leaf net photosynthetic rate,stomatal conductance,instantaneous water use efficiency and biomass accumulation above ground of Arabica coffee,while FDI decreased significantly,ADI and FDI increased irrigation water use efficiency by 50. 59% and 32. 85%,respectively. Compared with NH,with the reduction of N application rate,net photosynthetic rate,stomatal conductance,biomass accumulation above ground and irrigation water use efficiency decreased by 6. 81%-12. 30%,13. 70%-22. 69%,9. 61%-16. 67% and 9. 78%-15. 64%,respectively. Compared with CDINH,ADINHdecreased net photosynthesis rate and the stomatal conductance not significantly,other treatments decreased by 9. 16%-19. 22%,14. 49%-32. 91%,and decreased biomass accumulation above ground by 8. 26%-27. 34% except ADINH,and increased irrigation water use efficiency by 16. 46%-60. 95% except CDINMand CDINL. Therefore,alternate drip irrigation under high N level( ADINH) is the best water and nitrogen coupling mode of young Arabica coffee tree for water efficiency.

Response of Soil Organic Carbon and Its Aggregate Fractions to LongTerm Fertilization in Irrigated Desert Soil of China

Irrigated desert soil samples in the Hexi Corridor of China were collected over a period of 23 years from a site where different fertilization methods had been used. Changes of soil organic carbon （SOC） and its water stable aggregate （WSA） size fractions were studied. The effects of various fertilization methods on the distribution of added organic carbon （OC） in different WSA size fractions were also analyzed. The results showed that the applied fertilizations for 23 years improved SOC concentrations and OC concentrations in all WSA size fractions compared to the non-fertilized treatment （CK）. In addition, fertilization obviously increased the OC stocks of2 mm, 0.25-2 mm and 0.053-0.25 mm WSA fractions, respectively. A signiifcant positive correlation was found between soil C gains and OC inputs （r=0.92, P〈0.05）, indicating that SOC may have not reached the saturation point yet at the site. The C sequestration rate was estimated by 14.02%at the site. The OC stocks in all of the〈2 mm WSA fractions increased with the increase of OC input amounts;and the conversion rate of the input fresh OC to the OC stock of〈0.053 mm WSA fraction was 1.2 and 2.6 times higher than those of the 0.25-2 mm and 0.053-0.25 mm WSA fractions, respectively. Therefore, the〈0.053 mm WSA fraction was the most important component for soil C sequestration in the irrigated desert soil.

Effects of nitrogen application rates and irrigation regimes on grain yield and water use efficiency of maize under alternate partial rootzone irrigation

Faced with the scarcity of water resources and irrational fertilizer use,it is critical to supply plants with water and fertilizer in a coordinated pattern to improve yield with high water use efficiency(WUE).One such method,alternate partial root-zone irrigation(APRI),has been practiced worldwide,but there is limited information on the performance of different irrigation regimes and nitrogen(N)rates under APRI.The objectives of this study were to investigate the effects of varying irrigation regimes and N rates on shoot growth,grain yield and WUE of maize(Zea mays L.)grown under APRI in the Hexi Corridor area of Northwest China in 2014 and 2015.The three N rates were 100,200 and 300 kg N ha–1,designated N1,N2 and N3,respectively.The three irrigation regimes of 45–50%,60–65%and 75–80%field capacity(FC)throughout the maize growing season,designated W1,W2 and W3,respectively,were applied in combination with each N rate.The results showed that W2 and W3 significantly increased the plant height,stem diameter,crop growth rate,chlorophyll SPAD value,net photosynthetic rate(Pn),biomass,grain yield,ears per ha,kernels per cob,1000-kernel weight,harvest index,evapotranspiration and leaf area index(LAI)compared to W1 at each N rate.The N2 and N3 treatments increased those parameters compared to N1 in each irrigation treatment.Increasing the N rate from the N2 to N3 resulted in increased biomass and grain yield under W3 while it had no impact on those under the W1 and W2 treatments.The W3 N3 and W2 N2 and W2 N3 treatments achieved the greatest and the second-greatest biomass and grain yield,respectively.Increasing the N rate significantly enhanced the maximum LAI(LAI at the silking stage)and Pn under W3,suggesting that the interaction of irrigation and fertilizer N management can effectively improve leaf growth and development,and consequently provide high biomass and grain yield of maize.The W2 N2,W2 N3 and W3 N3 treatments attained the greatest WUE among all the treatments.Thus,either 60–65%FC coupled with 200–300 kg N ha–1 or 75–80%FC coupled with 300 kg N ha–1 is proposed as a better pattern of irrigation and nitrogen application with positive regulative effects on grain yield and WUE of maize under APRI in the Hexi Corridor area of Northwest China and other regions with similar environments.These results can provide a basis for indepth understanding of the mechanisms of grain yield and WUE to supply levels of water and nitrogen.

Effects of Alternative Partial Root-zone Irrigation and Nitrogen Fertilizer on Plukenetia volubilis Seedlings

This study was aimed to investigate the effects of alternative partial rootzone irrigation and nitrogen fertilizer on the potted seedlings of Plukenetia volubilis.A total of 7 treatments were designed with three factors, i.e., irrigation amount, irrigation mode and nitrogen fertilizer. The growth, photosynthesis and water use efficiency were analyzed. The results showed that compared with those under full irrigation, the biomass and water consumption under alternative partial root-zone irrigation were reduced by 5% and 75%, respectively, and the water use efficiency was increased by 60%. Under severe drought conditions, the root cap ratio in the nitrogen fertilizer treatment group was increased by 30%; the leaf area index, photosynthetic rate and biomass under alternative partial root-zone irrigation were reduced by 38%, 9% and 18%, respectively. It indicates that under severe drought conditions, alternative partial root-zone irrigation is not suitable to be matched with application of nitrogen fertilizer. In short, under moderate drought conditions, alternative partial root-zone irrigation could reduce transpiration and improve water use efficiency, and it is an effective water-saving irrigation technology for the plantation of P.volubilis plants.

LAND UTILIZATION COUNTERMEASURES AND CURRENT SITUATION OF HETAO IRRIGATION REGION IN INNER MONGOLIA

Hetao irrigation region is situated in the western part of Inner Mongolia. It stands bythe Yin·Shan mountain in the north, leans against the Yellow River in the south, nears theeastern side of Ulanbuhe Desert in the west and borders on Baotou in the east. It is 280kilometers in length from east to west. and 45-90 kilometers in width from north to south.

Planning for Integrative Management of Wastewater Disposal, Irrigation Water Supply and Fertilizer Use: A Case Study in an Arid Land of China

This work is a trans-disciplinary undertaking aiming at innovative water management in arid and semi-arid regions. Based on field studies on soil bacterial communities and irrigation water quality in an arid region of China where wastewater has been used for agricultural production decade long, this paper is intended to propose an integrative management scheme combining wastewater reuse in agriculture, wise use of wetlands and fertilizer management as an engine toward achieving sustainable development in arid and semi-arid regions. This study was also designed to address a key but very much neglected question about wastewater reuse in irrigation: does wastewater irrigation lead to reduction of chemical fertilizer use and increase of crop yield? Through a questionnaire, it revealed that there was a misperception among farmers about wastewater, which led to no-reduction or even increase in fertilizer use with wastewater irrigation as compared with river water irrigation. It also showed that crop yield was not increased with wastewater irrigation under the current practice. Besides, it sheds some light on an underreported health concern.

Effects of Different Drip Irrigation Fertilizers on Nutrient Levels in Celery and Soil under Drip Irrigation

This study was conducted to investigate the effects of different fertilizers on nitrogen, phosphorus and potassium ＇absorption and distribution by celeo, and the changes of soil nutrients in the 0 -40 cm soil layer under drip irrigation, so as to provide a theoretical basis for nutrient management of greenhouse celery culti- vation and special fertilizer development. With celery as an experiment material and the ratio of conventional fertilization as control treatment, the effects of different ratios of nitrogen, phosphorus and potassium on nutrient absorption by celery and changes of soil nutrients were investigated by plot experiment in greenhouse. The results showed that the contents and distribution proportions of N and P in leaf were higher than those in stem, while for K, the content and distribution proportion were higher in stem than in leaf. The absorption amount of K was the highest in celery, followed by N, and the absorption amount of P element was the least. The mean ratio of N, P and K in celery was 1：0.556： 1.609. There were evident dynamic changes in contents of soil available nutrients in the 0 -20 cm soil layer in various growth stages of celery under different drip irrigation fertilizers. The contents of soil available nutrients were higher on the 28＇h , 47~ and 83＇h d ＂after fieht planting, while those before field planting and after harvest were lower. So the amounts of soil available nutrients were closely related to the growth stage of celery. In the whole growth period of celery, the mean input amounts of N, P205 and K20 were 805, 1 049 and 916 kg/hm2 , respectively, but the absorption amounts of nutrients by celery were far less than inputs, and the amounts of N, P205 and K20 absorbed by celery＂ were only 23% -26% , 10% and 31% -35% of the appli- cation amounts, respectively. The apparent balance of N, P2 O5 and Kz O were 613,943 and 609 kg/hm2 , respectively, indicating excess fertilization in this experi- ment. Under this experiment condition, Tj （ N： PzOs： K20 = 1 ： 0.63： 1.08） favored increase of celery yield and absorption of nitrogen, phosphorus and petassium by celery. The results will provide a scientific basis for study and utilization of special fertilizer for drip irrigation on celery. Key words Drip irrigation; Fertilizer for drip irrigation; Celery; Soil nutrient; Apparent balance

Distribution Characteristics of the Heavy Metal Cd in the Irrigation Water-Cultivated Soil-Fertilizer-Crop Ecosystem

Shuangqiao Countryside of Neijiang City in hilly ground area in the midland of Sichuan Province was chosen as the study geographic area to survey and analyze the content distribution characteristics of the Cd in the irrigation water,ground water mud,surface layer cultivated soil,profile soil and the fertilizer which were often used in the locality,and in different crops set earth,fructification as well. The results showed that the content of Cd in the irrigation and ground water mud respectively comply with the national agriculture use irrigation standard and the contamination control standard value in agriculture use mud ( GB4284-84) respectively. The average contents in the surface cultivated soil and each layer of soil profile are all above the background level of Chengdu economic region ( 44% ) ,referring to a large scale pollution risk. The average value of Cd element in fertilizer was 1. 81 μg / g,which was higher than the third class standard of national soil environment quality; The average content of Cd element in the crops' set earth was 0. 410-0. 439 μg / g,which was higher than the second class standard of national soil environment quality and there was a measure of cumulation; The average values of Cd in crops' fructificationwas all below the primary standard of national soil environment quality,and the bioamplification coefficient sorting was CF( Cdpeanut) > CF( Cdcitrus) > CF ( Cdrice) > CF( Cdcorn) . Irrigation water had little influence on the soil Cd pollution,where fertilizer using was closely related to the Cd pollution in the surface cultivated soil in the survey area and had a certain influence on the Cd cumulation in the crops. The sorption and enrichment of crops' set earth and fructification was obviously different.

Competitiveness and Profitability of Intercropping Sunflower with Peanut under Different Irrigation Water Levels and Potassium Fertilizer Rates

A two-year study was carried out at Ismailia Agricultural Research Station, Egypt during 2016 and 2017 summer seasons to evaluate competitive effects of intercropping sunflower and peanut under different drip irrigation water amounts and K fertilizer rates for increasing farmer profitability. Three irrigation amounts (70%, 100% and 120% ETo), three K fertilizer levels (57, 86 and 114 K2O kg/ha) and four intercropping patterns of sunflower and peanut (different spatial arrangements) were implemented. The experimental design was strip split plot with three replications. The results showed that there were no significant differences between 100% and 120% ETo on most of yield traits of the intercrops. The highest K fertilizer level had the highest values of most yield traits of the intercrops. The highest values of peanut and sunflower traits were obtained from intercropping sunflower with peanut, where peanut seeds were sown on both sides of all the raised beds, sunflower seeds were sown on one row above the raised beds and the following bed was left without intercropping (P1). Thus, to attain the highest yield of intercrops and water equivalent ratio (WER), the lowest competitive pressure and the highest farmer profitability, 120% ETo, 114 K2O kg/ha and P1 intercropping pattern should be implemented. This research found that the result of competitiveness was consistent with the result of profitability.

Evaluating the Effects of Aquaculture Wastewater Irrigation with Fertilizer Reduction on Greenhouse Tomato Production,Economic Benefits and Soil Nitrogen Characteristics

The utilization of aquaculture wastewater as irrigation is an effective way to recycle and reuse water and nitrogen fertilizer resources because it contains numerous nutrients.However,it is still unclear that the pattern of substituting aquaculture wastewater irrigation for fertilizer supplementing is conducive to improving the soil nitrogen status,fruit yield and water-fertilizer use efficiency for tomato production.In this context,the experiment was intended to establish the appropriate irrigation regime of aquaculture wastewater in tomato production for freshwater replacement and fertilizer reduction to ensure good yields.Pot experiments were conducted with treatments as farmers accustomed to irrigation and fertilization used as control(CK),1.75 L aquaculture wastewater with base fertilizer(W1),2 L aquaculture wastewater with base fertilizer;and 2.25 L aquaculture wastewater with base fertilizer(W3).We examined the effects of aquaculture wastewater irrigation on soil nitrogen distribution,Nrelated hydrolases,tomato yield,and economic benefits.The results showed that the control treatment had the highest N input,about 24.68%higher than the W3 treatment,while the yield was only about 7.81%higher than W3.This indicated that the overuse of chemical fertilizer was present in the current tomato production.Although the reduction of fertilizer in aquaculture wastewater irrigation caused a decrease in tomato production,this economic loss can be compensated by cost savings in the wastewater disposal.Among aquaculture wastewater treatments,the W3 treatment had the highest overall benefit,achieving 62.63%freshwater savings,37.50%fertilizer input reduction,and an economic return of approximately 19,466 Yuan per hectare higher than the control.Additionally,increasing the irrigation volume of aquaculture wastewater could provide more available nutrients to the soil,which were more prevalent in the form of organic nitrogen.The lower soil nitrate reductase activities(NR)under aquaculture wastewater treatments after harvesting also proved that this pattern was beneficial to reduce soil nitrate nitrogen residues.Overall,the results demonstrate that aquaculture wastewater irrigation alleviates the soil nitrate residues,improves nutrient availability,and results in more economic returns with water and fertilizer conservation for the greenhouse production of tomatoes.

Growth Parameters of DK8031 Maize Variety as Affected by Varying Irrigation and Nitrogen Fertilizer Rates in Embu County, Kenya

Determination of crop growth parameters of maize helps assess the performance of the crop for food security. A study was conducted in two seasons covering 2012 and 2013 to establish optimal irrigation and nitrogen fertilizer rates for drought tolerant hybrid maize （Zea mays L.）, DK8031 variety, in sandy loam soils using furrow irrigation. Four additive irrigation levels （119.05 mm, 238.10 mm, 357.15 mm and 476.2 mm） were allocated the main plots while five nitrogen fertilizer rates （0 kg/ha, 60, 75 kg/ha, 90 kg/ha and 100 kg/ha） were allocated the sub-plots. Both irrigation and nitrogen fertilizer treatments significantly enhanced crop growth parameters under consideration. Stand count per treatment plot, plant height and number of leaves per ranged from 45-59 plants/plot, 215-238 cm and 14-16 leaves respectively. It was concluded that use of supplementary irrigation and phased nitrogen fertilizer rates for maize growing in areas such as Embu can greatly promote crop growth.

Water and nitrogen transport characteristics of single-line interference infiltration under film hole irrigation with muddy water and fertilizer

Based on the experimental data,this study investigated the effect of sand content of muddy water on water and nitrogen transport characteristics of the single-line interference infiltration under film hole irrigation with muddy water and fertilizer.The relationship between the single-line interference infiltration parameters,the sand content,the wetting front movement distances,and the sand content were all established.The model of the cumulative infiltration volume of per unit film pore area,the vertical and horizontal wetting front movement distance of the free surface,and the wetting front movement distance of the interference center with sand content and infiltration time were proposed.Reveal the law of the change of soil water content and the distribution of NO_(3)^(-)-N content based on different muddy water sand content.The results indicate that at the same infiltration time,as the muddy water sand content increases,the cumulative infiltration volume per unit pore area decreases.The infiltration index of the free infiltration and the single-line interference vary little when the sand content increases,mainly are around 0.64 and 0.58.The relationship between infiltration parameters a,b and the sand content is linear function.At the same location,the more the sand content,the smaller the wetting front movement distance in free surface and the single-line interference surface,the less the NO_(3)^(-)-N content.