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.

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.

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.

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 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.

Interactions of Water Management and Nitrogen Fertilizer on Nitrogen Absorption and Utilization in Rice

The interactions of water management and nitrogen fertilizer on nitrogen absorption and utilization were studied in rice with Wuxiangjing9 (japonica). The results showed that the nitrogen uptake and remaining in straw increased and the percentage of nitrogen translocation (PNT) from vegetative organs, nitrogen dry matter production efficiency (NDMPE) and nitrogen grain production efficiency (NGPE) decreased with nitrogen increasing. The nitrogen uptake and NGPE decreased when severe water stressed. However, rice not only decreased the nitrogen uptake but also increased the PNT from vegetative organs, NDMPE and NGPE when mild water stressed. There were obvious interactions between nitrogen fertilizer and water management, such as with water stress increasing the effect of nitrogen on increasing nitrogen uptake was reduced and that on decreasing NDMPE was intensified.

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.

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.

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.

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.

Cotton Response to Variable Nitrogen Rate Fertigation through an Overhead Irrigation System

Recent increases in irrigated hectares in the Southeastern US have enabled growers to obtain higher yields through applying nutrients through irrigation water. Therefore, many growers apply nutrients through irrigation systems, known as fertigation. Currently, there are no practical decision-making tools available for variable-rate application of nitrogen (N) through overhead sprinkler irrigation systems. Therefore, field tests were conducted on cotton (Gossypium hirsutum L.) during the 2016 and 2017 growing seasons to 1) adapt the Clemson sensor-based N recommendation algorithms from a single side-dress application to multiple applications through an overhead irrigation system;and 2) to compare sensor-based VRFS with conventional nutrient management methods in terms of N use efficiency (NUE) and crop responses on three soil types. Two seasons of testing Clemson N prediction algorithms to apply multiple applications of N were very promising. The multiple applications of N compared to the grower’s conventional methods (even though less N was applied) had no impact on yields in either growing season. There was no difference in cotton yields between 101 and 135 kg/ha N applications in either management zone. Also, there were no differences in yield between sensor-based, multiple N applications and conventional N management techniques. In relation to comparisons of the sensor methods only applying N in three or four applications, statistically increased yields compared to single or split applications in 2016. Applying N in four applications, statistically increased yields compared to single, split or triple applications in 2017. When the sensor-based methods were compared to the grower’s conventional methods averaged over four treatments, the sensor-based N applications reduced fertilizer requirement by 69% in 2016 and 57% in 2017 compared to grower’s conventional methods. When comparing N rates among the four sensor-based methods (three or four) applications, increased N rates by 22 kg/ha in 2016 and 26 kg/ha in 2017 compared to single or split applications but increased the cotton lint yields by 272 and 139 kg/ha, for 2016 and 2017, respectively.

灌溉量和氮肥增效剂对夏玉米产量及水肥利用的影响

为探究水分和氮肥增效剂对夏玉米生长及水肥利用的综合影响,通过设置40 mm(W1)和60 mm(W2)两个灌水水平下不施氮肥(N0)、施用氮肥(U)、氮肥+硝化抑制剂(U+DCD)、氮肥+脲酶抑制剂(U+NBPT)、氮肥+双效抑制剂(U+N+D)5种氮肥施用措施,开展夏玉米田间试验。结果表明:相较于施用氮肥处理,氮肥配施增效剂可以显著提高夏玉米产量、成熟期地上生物量、净收益、水分利用效率和氮肥偏生产力,增幅分别为5.92%~13.82%、5.85%~18.07%、11.12%~24.30%、12.35%~41.83%和5.93%~13.80%,其中氮肥配施双效抑制剂效果较优;氮肥配施脲酶抑制剂和双效抑制剂可以降低夏玉米农田土壤氨挥发累积量和成熟期土壤硝态氮残留量,前者效果最优。相比于W1,W2水平下氮肥配施双效抑制剂处理玉米产量、成熟期地上生物量、净收益、水分利用效率和氮肥偏生产力分别提高10.54%、15.51%、19.40%、20.31%和27.36%;氮肥配施脲酶抑制剂处理农田土壤氨挥发累积量和硝态氮残留量分别降低11.33%和48.46%。综合考虑夏玉米施肥灌水方案的经济效益、环境效益、水肥利用效率和玉米植株生长,构建模糊综合评价体系,得到最优处理为灌水量60 mm下氮肥配施双效抑制剂。

不同灌溉施肥方式对夏玉米产量和水氮利用的影响

为明确不同灌溉施肥方式对夏玉米生长、产量及水氮利用的影响,本试验以登海605(DH605)和郑单958(ZD958)为材料,设常规灌溉施肥(FP)、喷灌+种肥同播(SN)、喷灌+水肥一体化(SF100%)、喷灌+水肥一体化+减氮20%(SF80%)共4个处理,研究不同灌溉施肥方式对夏玉米干物质积累、产量及产量构成因素、水分利用效率和氮肥偏生产力的影响。结果表明,品种、灌溉施肥方式及品种和灌溉施肥互作效应显著影响夏玉米的产量、干物质积累速率、水分利用效率(WUE)和氮肥偏生产力(PFPN),SF80%处理下两年平均产量、水分利用率、氮肥偏生产力均最高。与FP、SN和SF100%处理相比,SF80%处理下DH605两年平均产量分别提高14.55%、7.66%和2.26%,水分利用率分别提高23.73%、12.61%和8.86%,氮肥偏生产力分别提高43.19%、34.58%和27.82%;ZD958两年平均产量分别提高35.93%、15.24%和7.84%,水分利用率分别提高40.81%、21.79%和11.13%,氮肥偏生产力分别提高69.91%、44.05%和34.80%。综上所述,喷灌+水肥一体化+减氮20%的灌溉施肥方式可以显著提高夏玉米产量和水氮利用效率,实现夏玉米增产增效。

鸟粪石基载镁生物炭对干湿交替灌溉水稻产量与品质的影响

鸟粪石(MgNH4PO_(4)·6H2O)普遍存在于镁改性生物炭对废水氮磷去除后的回收产物中,其可以作为缓释肥料使用。为探究鸟粪石基载镁生物炭(struvite-based magnesium modified biochar,MAP-BC)在农田中的应用效果以及对不同灌溉和施肥模式的适用性,该研究依托大田试验,以东研18号(粳稻)为供试材料,设置常规淹灌(ICF)、干湿交替(IAWD)2种灌溉模式,以及常规施肥(conventional fertilization,N_(1)B_(0))、常规施肥+5 t/hm^(2)MAP-BC(conventional fertilization+5 t/hm^(2)MAP-BC,N_(1)B_(1))、常规施肥+10 t/hm^(2)MAP-BC(conventional fertilization+10 t/hm^(2)MAP-BC,N_(1)B_(2))、减施氮磷肥25%+5 t/hm^(2)MAP-BC(25%less nitrogen and phosphate fertilizer+5 t/hm^(2)MAP-BC,N_(3/4)B_(1))和减施氮磷肥25%+10 t/hm^(2)MAP-BC(25%less nitrogen and phosphate fertilizer+10 t/hm^(2)MAP-BC,N_(3/4)B_(2))5种施肥模式。结果表明:与ICF相比,IAWD显著提高了乳熟期叶片叶绿素含量,并显著降低了2021年无效分蘖数(P<0.05);MAP-BC不仅能够高效弥补减施氮磷肥对水稻叶绿素含量的不利影响,还具有一定的超补偿效果;MAPBC中高纯度的鸟粪石组分通过缓释氮磷素,保障了对植株氮磷养分的长期供应。与N_(1)B_(0)相比,N_(3/4)B_(2)不仅可以满足水稻生长后期对氮磷养分的需求,还使穗部吸氮量和吸磷量分别显著增加(P<0.05)4.77%~7.06%和4.26%~12.69%;与N_(1)B_(0)相比,施加10 t/hm^(2)MAP-BC使2a的最高分蘖数和最终分蘖数分别显著增加(P<0.05)6.75%~9.64%和13.16%~16.88%;2 a试验中,在IAWD模式下,与N_(1)B_(0)相比,N_(1)B_(1)和N_(1)B_(2)的产量分别显著提高(P<0.05)了7.66%~8.43%和11.49%~12.64%,并且10 t/hm^(2)的MAP-BC可以弥补减施25%氮磷肥对产量造成的不利影响;IAWD模式下N_(3/4)B_(1)和N_(3/4)B_(2)可以显著降低消减值、垩白粒率和垩白度,显著提高崩解值,从而显著改善(P<0.05)水稻外观品质与食味值;此外,N_(1)B_(1)和N_(1)B_(2)较N_(1)B_(0)处理显著提高(P<0.05)稻米蛋白含量2.66%和5.79%,表明施用MAP-BC有助于改善稻米的营养品质。因此,在IAWD模式下减施氮磷肥25%配施10 t/hm^(2)MAP-BC可在节水条件下实现减施氮磷肥、增产、提质,从而为水稻绿色高效生产提供理论依据。

有机肥替代氮肥对银北灌区盐化灌淤土理化性质及玉米生长的影响

次生盐渍化已成为宁夏银北灌区灌淤土壤退化的主要形式,制约着宁夏农业持续高质量发展。为了给宁夏地区盐化灌淤土的施肥管理及提高作物产量提供科学依据,以银北灌区典型盐化灌淤土为研究对象、玉米品种先玉335为指示品种,研究了不同施肥水平对盐化灌淤土土壤理化性质及玉米生长的影响。结果表明,各施肥处理均能有效地增加盐化灌淤土的速效养分含量,进而优化玉米产量构成要素,提高玉米产量。各施肥处理除常规施肥处理(施N 375.0 kg/hm^(2)、P_(2)O_(5)100.0 kg/hm^(2)、K_(2)O 100.0 kg/hm^(2))的玉米总根长、根表面积最高外,有机肥替代常规施肥量50%氮肥(施N 187.5 kg/hm^(2)、P_(2)O_(5)100.0 kg/hm^(2)、K_(2)O 100.0 kg/hm^(2)、有机肥7.3 t/hm^(2))处理的土壤理化性质及玉米生长指标最高。与对照不施肥相比,该处理下土壤有机质、速效氮、速效磷、速效钾分别增加了34.5%、25.9%、120.5%、23.7%,玉米穗长、穗粗、穗粒数、产量分别增加了40.5%、15.2%、80.5%、104.8%,秃尖长降低了78.0%;与常规施肥处理相比,该处理下土壤有机质、速效氮、速效磷、速效钾分别增加了36.5%、21.4%、13.7%、8.6%,玉米穗长、穗粗、穗粒数、产量分别增加了0.6%、1.9%、5.3%、3.1%,秃尖长降低了57.7%。综合分析,不同施肥水平均可改善盐化灌淤土理化性质进而提升玉米产量,且以有机肥替代部分氮肥施用的处理效果较好,其中以有机肥替代常规施肥量50%氮肥的施肥水平效果最好。

垄作灌溉和减施氮肥对稻田CH_(4)排放、土壤有机酸含量和酶编码基因表达量的影响

【目的】研究不同垄面宽度的垄作灌溉和不同时期减施氮肥对稻田甲烷(CH4)排放、土壤有机酸含量以及CH4形成和转化相关酶编码基因(产CH4古菌中甲基辅酶M还原酶编码基因mcrA和CH4氧化菌中CH4单加氧酶编码基因sMMO)表达量的影响,揭示土壤有机酸以及mcrA和sMMO表达量对稻田CH4通量的影响。【方法】开展3种灌溉模式(淹水灌溉,垄宽分别为80、100 cm的垄作灌溉)和3种施氮处理(常规施氮:135 kg·hm^(−2),其中苗肥47.25 kg·hm^(−2)、分蘖肥54.00 kg·hm^(−2)和穗肥33.75 kg·hm^(−2);返青期减氮:110 kg·hm^(−2),其中苗肥22.25 kg·hm^(−2)、分蘖肥54.00 kg·hm^(−2)和穗肥33.75 kg·hm^(−2);孕穗期减氮:110 kg·hm^(−2),其中苗肥47.25 kg hm^(−2)、分蘖肥54.00 kg hm^(−2)和穗肥8.75 kg hm^(−2))的田间试验,测定生育期内稻田CH4通量、土壤有机酸含量以及mcrA和sMMO表达量,分析稻田CH4通量、土壤有机酸含量以及mcrA和sMMO表达量之间的相互关系。【结果】相同施氮处理下,垄作灌溉稻田CH4排放量较淹水灌溉显著降低,相同灌水模式下,返青期减氮稻田CH4排放量较常规施氮显著降低。垄宽为80 cm的垄作灌溉+常规施氮处理在施肥后10 d土壤总有机酸含量较施肥前高71.7%,淹水灌溉和常规施氮处理高28.8%。返青期减氮下,垄宽为80 cm的垄作灌溉土壤mcrA表达量整体低于淹水灌溉,sMMO表达量除移栽后25 d外均高于淹水灌溉。稻田CH4通量与土壤mcrA表达量和总有机酸含量显著相关(P<0.01),相关系数分别为0.644和−0.348,土壤总有机酸含量与mcrA、sMMO表达量显著相关(P<0.05),相关系数分别为−0.240和0.197。【结论】垄宽80 cm垄作灌溉+返青期减氮处理降低了稻田CH4通量,土壤总有机酸含量和mcrA表达量显著影响稻田CH4通量,sMMO表达量可能间接影响稻田CH4通量。

番茄嫁接和施氮对氮肥去向和氮平衡的影响

【目的】定量番茄植株地上部带走的土壤氮量以及土壤残留的肥料氮量,评估嫁接和施氮对氮肥去向、土壤氮平衡以及土壤净残留肥料氮的影响。【方法】通过15N尿素示踪结合盆栽试验,试验番茄品种‘齐达利’和‘017’,包括嫁接和不嫁接以及施氮和不施氮处理。借助15N标记技术区分植株和土壤中源于肥料氮和土壤氮的贡献,进而追踪肥料氮去向;计算土壤氮吸收的加氮交互效应(即施氮与不施氮植株对土壤氮吸收的差值),最终评估土壤氮的平衡。【结果】番茄植株干重和氮吸收量对施氮的响应取决于接穗品种和嫁接处理。肥料氮对整个植株氮吸收贡献率为35.9%—38.8%,对地上部氮吸收的贡献(35.9%—39.9%)高于根系(31.6%—36.2%)。土壤氮吸收的加氮交互效应在大多数情况下呈现正值,嫁接对加氮交互效应无显著影响。各处理肥料氮分配到植株地上部、土壤和损失的平均比值为4.0﹕2.6﹕3.4,作物-土壤系统对氮肥的总回收率(地上部吸收+土壤残留)为70%。在施氮量250 kg·hm^(-2)水平,各处理的土壤残留肥料氮无法弥补植株地上部带走的土壤本身氮,从长期来看,这可能导致土壤本身氮肥力的消耗。【结论】如果选择增加氮肥投入来弥补土壤本身氮的消耗,可能导致氮肥损失的风险。本研究中,与番茄‘齐达利’自根苗、‘017’自根苗和嫁接苗相比,‘齐达利’接穗与南瓜砧木组合增加了根际土壤对肥料氮的固持,降低了肥料氮的损失。因此,合适砧穗组合可能是保持番茄土壤氮肥力的有效园艺措施。

绿洲灌区密植对氮肥减量玉米产量的补偿潜力

【目的】针对绿洲灌区玉米生产氮肥用量过高的问题,探究通过密植补偿氮肥减量对玉米产量负效应的可行性。【方法】2019—2021年,以施氮水平为主区,设地方习惯施氮(N_(2),360 kg·hm^(-2))、减量25%施氮(N_(1),270 kg·hm^(-2))两个水平;以种植密度为副区,设传统(M_(1),7.8万株/hm^(2))、中(M_(2),10.4万株/hm^(2),增密33%)、高(M3,12.9万株/hm^(2),增密66%)3个密度水平,进行裂区试验,重点研究氮肥减量条件下增密对玉米产量及其构成因素的影响。【结果】(1)氮肥减量导致玉米籽粒产量、生物产量分别降低4.0%、4.9%。减氮条件下,中密度可以产生籽粒产量补偿效应,N_(1)M_(2)较对照N_(2)M_(1)提高4.1%;高密度处理N_(1)M3生物产量补偿效应最大,较对照提高14.2%。(2)通过回归分析模拟得到:减氮条件下,当种植密度提高至8.4万株/hm^(2)可以与对照N_(2)M_(1)籽粒产量持平,并在10.6万株/hm^(2)时获得最大产量13537kg·hm^(-2),较对照提高4.9%。(3)氮肥减量引起穗数、穗粒数和千粒重分别降低5.0%、3.3%和3.4%;中、高密度分别较传统密度提高穗数27.9%、49.7%,降低穗粒数3.8%、8.4%,降低千粒重5.2%、8.9%。中密度较传统密度对收获指数无显著影响,而高密度使收获指数降低14.2%。N_(1)M_(2)较对照N_(2)M_(1)通过穗数增加补偿了减氮引起穗数、穗粒数及千粒重的下降,从而实现丰产。(4)氮肥减量降低拔节期至抽雄吐丝期的玉米生长率7.2%—8.4%;中、高密度较传统密度提高苗期至大喇叭口期玉米生长率27.3%、60.3%。(5)氮肥减量条件下,N_(1)M_(2)较对照提高叶、茎和鞘干物质转运量达9.6%、13.6%和3.7%,提高叶和茎对籽粒产量的贡献率5.3%和9.0%。【结论】通过合理密植可以补偿减氮引起的玉米产量下降,在施氮量270 kg·hm^(-2)的基础上增密至10.4万株/hm^(2),能够最大化产量补偿效应,是绿洲灌区玉米节氮稳产丰产的可行措施。

华北平原夏玉米喷灌施氮制度优化

不合理的氮肥施用和较大的降雨量时空变化特征是限制华北平原夏玉米增产和肥料利用效率提高的关键因素。为探究华北平原夏玉米最优喷灌施肥管理制度,于2020年和2021年在河北省邢台市大曹庄管理区开展试验,以地面灌溉肥料撒施处理为对照,研究了喷灌施肥下3种施氮量确定方法(农户经验值、养分平衡法和改进养分平衡法)和3种氮肥追施方法(不追肥、在大喇叭口-灌浆期内较大降雨后追施1次和追施2次)对土壤水氮分布、作物生长、产量以及氮肥利用效率的影响。结果表明,受降雨影响,夏玉米生育期内0~100 cm土层的土壤含水率始终保持在较高水平。施氮量和氮肥追施次数的增加均提高了夏玉米关键需肥阶段根区的土壤无机氮含量,且喷灌处理的增加量大于对照处理。2 a夏玉米收获后,养分平衡法确定施氮量处理和氮肥全部基施处理的土壤氮素残留量均低于参考盈余水平(50 kg/hm^(2))。不同处理叶面积指数未出现显著差异,但氮肥追施2次的喷灌处理显著增加了玉米干物质量和植株吸氮量,产量和氮肥偏生产力均分别比对照处理显著提高了20%。考虑氮素盈余的改进养分平衡法和在大喇叭口期-灌浆期内较大降雨后追施2次的施肥方法有助于维持土壤氮库平衡,且具有显著的增产和氮肥利用效率提高作用,可推荐为华北平原夏玉米喷灌施肥制度。研究可为大型喷灌机在华北平原的推广应用提供参考。

不同耕作灌溉和有机肥替代下稻田有机碳和氮磷潜在排放特征

通过盆钵试验研究了不同耕作条件、不同灌溉方式和基肥期有机肥替代对水稻田面水有机碳与氮磷浓度、潜在可排放量及水稻产量的影响。结果表明:1)浅水灌溉相比常规灌溉,在旋耕时各项指标的平均可排放量均呈现不同程度的降低趋势,其中化学需氧量(COD)降低43.43%,可溶性有机碳(DOC)降低43.19%,总氮(TN)降低46.52%,总磷(TP)降低60.34%;而翻耕时稻田田面水的COD、DOC、TN和TP浓度分别降低22.73%、41.58%、31.58%和31.25%。2)翻耕相比旋耕,在常规灌溉时稻田田面水COD、DOC和TP的平均可排放量分别降低16.02%、15.67%和23.71%;在浅水灌溉时稻田田面水COD、DOC和TP的平均可排放量分别降低43.42%、16.81%和13.93%。3)浅水灌溉下有机肥替代氮肥用作基肥的田面水COD、DOC和TP的平均可排放量无显著差异(P>0.05);浅水灌溉相比常规灌溉,在旋耕和翻耕时水稻产量分别减产20.63%和6.88%。总之,浅水灌溉田面水碳、氮、磷排放风险显著低于常规灌溉,翻耕可以有效降低田面水碳、氮、磷排放风险,从稻田田面水防控和产量角度,浅水灌溉并翻耕能够在保证水稻产量的同时有效降低田面水养分流失风险。研究结果可为稻田投入品优化施用和田间水分及养分管理提供技术支撑。