水肥一体化中水肥混合效果数值模拟研究

为研究水肥一体化技术中的水肥混合特性,以流体力学中的两相流理论为基础,针对水肥混合过程中混合时间、混合区间长度、流速及管径对其混合效果的影响进行相应的数值模拟研究。结果表明,混合时间及混合区间长度越长有利于提高水肥混合效果及最终水肥混合均匀性;水肥流速比较低时管内水肥混合的均匀性较好,且水肥流速越大则其混合效果及均匀性越好;水肥流速较低时输水管及输肥管的管径比对水肥混合均匀性的影响较大,两者管径比越小则混合效果越好,随着流速的提高两者管径比对其混合效果的影响逐渐减弱。     

山地滴灌下矮化密植枣树氮磷钾施肥效应模式研究

采用氮、磷、钾三因素D饱和最优设计,研究了黄土高原山地滴灌下矮化密植枣树氮、磷、钾施肥肥效与优化施肥模式。结果表明,施肥明显促进了枣树地径的增加(单施钾肥除外),显著提高了红枣坐果率;施肥促进了新梢的生长,其中施氮和氮磷钾配施影响显著,而单施磷、单施钾影响不显著。施肥明显提高红枣产量,氮、磷、钾肥对红枣产量的影响为氮肥钾肥磷肥;氮肥与磷肥、氮肥与钾肥之间有正交互作用,磷肥与钾肥无明显交互作用。山地滴灌工程下矮化密植枣树(1 650株/hm2)目标产量为20 000~24 000kg/hm2的优化施肥方案为:N、P2O5、K2O施用量分别为271.36~374.88、128.36~217.94、124.44~228.58kg/hm2。     

滴灌施肥技术对菠萝生长发育的影响

以“巴厘”品种菠萝为材料,通过田间试验对比分析滴灌施肥管理与常规管理对菠萝生长发育的影响。结果表明,滴灌施肥技术能够促进主要营养器官的生长,叶片数、叶面积指数、茎长、干物质累积量以及果实的膨大速度和果实大小显著高于常规管理,最终提高菠萝产量（较常规管理提高39.04%）。     

滴灌施肥对幼龄茶树生长和养分吸收的影响

通过田间试验,研究了龙井43、白叶1号品种茶园滴灌施肥对幼龄茶树生长、养分吸收、品质成分等的影响,分析了不同施肥模式下的施肥成本投入情况。结果表明,与常规开沟施肥相比,采用滴灌施肥后,即使在化肥减量25%的情况下,树高、主干直径、树幅都显著增加,修剪物生物量增加明显;茶树对养分的吸收量明显增加,而养分的渗漏损失明显减少,从而提高了养分利用效率。从滴灌施肥的次数上分析,龙井43品种,在试验条件下年施肥次数7次可以达到较好效果,而白叶1号品种,年施14次的效果较好。     

氮肥减量后移对喷灌玉米产量和水氮利用效率的影响

【目的】优化井灌区田间水肥管理。【方法】试验于2018年6—9月在河南省许昌灌溉试验站进行,以当地主栽玉米品种登海3737(P1)和豫单9953(P2)为试验材料,设置3种施肥调控方式,分别为当地传统施肥模式CK(N、P2O5、K2O施量分别为315、75、75 kg/hm^2,全部基施),优化模式F1(N、P2O5、K2O施量分别为225、75、75kg/hm^2,40%三叶期和60%拔节期追肥),优化模式F2(N、P2O5、K2O施量分别为225、75、75kg/hm^2,30%三叶期、30%拔节期和40%大喇叭口期追肥),研究了喷灌水肥一体化下氮肥减量后移对不同品种夏玉米生长发育、产量和水分利用效率的影响。【结果】增加施肥频次和施肥时间后移可提高玉米叶面积系数(LAI)和延缓叶片衰老,增加玉米干物质累积量以及最大生长速率。喷灌水肥一体化(F1、F2处理均值)较传统施肥籽粒产量提高7.8%,耗水量降低11.9%,水分利用效率(WUE)提高22.2%,籽粒氮肥偏生产力(PFPY)提高51.1%,生物量氮肥偏生产力提高49.2%。登海3737干物质累积、最大生长速率、WUE和PFPY的均值较豫单9953分别增加2.8%、7.7%、8.5%和8.6%,最大生长速率出现的时间没有差异。豫单9953干物质积累快增期持续时间比登海3737增加5.3 d。不同品种之间产量和构成要素差异极显著。登海3737平均产量为11 319 kg/hm^2,较豫单9953增产8.4%,其中穗长、百粒质量对产量贡献较大,分别提高22.5%和18.2%。【结论】本研究中,F2处理为最佳施肥模式,即N、P2O5、K2O施量分别为225、75、75 kg/hm^2,施肥配比为30%三叶期、30%拔节期、40%大喇叭口期。     

施肥浓度对摇臂式喷头喷灌施肥均匀性的影响

为了研究施肥浓度对喷灌施肥均匀性的影响规律,选用摇臂式喷头10PY₂H,测量其喷灌施肥时肥液体积、施肥浓度、施肥量3种参数的径向分布.试验中,氯化钾溶液质量浓度(即母液浓度)分别为0,20,35,50,65,80 g/L.采用叠加法计算组合喷洒时3种施肥参数的均匀度CU、分布均匀度DU和统计均匀度U_s.分析表明施肥浓度对摇臂式喷头的灌水施肥影响呈现非线性特点.增加母液浓度对肥液体积分布和施肥浓度分布均匀性的影响相对较小,但对施肥量分布均匀性的影响十分显著.组合喷灌加剧了不同测点的数值差异.随着母液浓度增大,施肥量径向分布变化增大,当母液质量浓度增大到80 g/L时,施肥量主要集中在20%~60%射程处,导致施肥均匀性急剧下降;当母液质量浓度小于等于35 g/L时,远端90%~100%射程处的施肥浓度相对更高,与前人得出的滴灌施肥系统施肥浓度沿管道方向递减的规律相反.3个评价指标中,均匀度CU数值最高,分布均匀度DU总体数值最低、变化最大,且以DU变化最为明显,这说明了DU能反映低值区的施肥情况.喷灌施肥等值线图表明肥液与施肥量的分布规律相似,但施肥浓度的分布情况则相反,这可能与射程远端施肥浓度更大有关.     

茶园滴灌施肥的增产提质及土壤养分效应研究

以常规施肥作为对照,设计3个不同氮素用量(450、300、150 kg/hm2),研究了茶园滴灌施肥对茶叶产量、品质及土壤养分性状的影响。结果表明,滴灌施肥处理比对照增产3.4%～9.3%,施氮量与产量间呈明显正相关,以年施氮量300～450 kg/hm2产量较高,滴灌施肥对茶叶品质影响不显著。滴灌施肥处理成熟叶含氮量显著高于对照,且季节性差异明显,秋茶﹥夏茶﹥春茶,滴灌施肥可促进茶树对氮素的吸收利用。施肥方式对土壤pH值影响显著,滴灌施肥处理土壤pH值明显高于对照,可能因其氮素利用率较高而有助于减弱无机氮对土壤的酸化作用。     

Effect of fertigation frequency on soil nitrogen distribution and tomato yield under alternate partial root-zone drip irrigation

Alternate partial root-zone drip fertigation (ADF) is a combination of alternating irrigation and drip fertigation, with the potential to save water and increase nitrogen (N) fertilizer efficiency.  A 2-year greenhouse experiment was conducted to evaluate the effect of different fertigation frequencies on the distribution of soil moisture and nutrients and tomato yield under ADF.  The treatments included three ADF frequencies with intervals of 3 days (F3), 6 days (F6) and 12 days (F12), and conventional drip fertigation as a control (CK), which was fertilized once every 6 days.  For the ADF treatments, two drip tapes were placed 10 cm away on each side of the tomato row, and alternate drip irrigation was realized using a manual valve on the distribution tapes.  For the CK treatment, a drip tape was located close to the roots of the tomato plants.  The total N application rate of all treatments was 180 kg ha–1.  The total irrigation amounts applied to the CK treatment were 450.6 and 446.1 mm in 2019 and 2020, respectively; and the irrigation amounts applied to the ADF treatments were 60% of those of the CK treatment.   The F3 treatment resulted in water and N being distributed mainly in the 0–40-cm soil layer with less water and N being distributed in the 40–60-cm soil layer.  The F6 treatment led to 21.0 and 29.0% higher 2-year average concentration of mineral N in the 0–20 and 20–40-cm soil layer, respectively and a 23.0% lower N concentration in the 40–60-cm soil layer than in the CK treatment.  The 2-year average tomato yields of the F3, F6, F12, and CK treatments were 107.5, 102.6, 87.2, and 98.7 t ha–1, respectively.  The tomato yield of F3 was significantly higher (23.3%) than that in the F12 treatment, whereas there was no significant difference between the F3 and F6 treatment.  The F6 treatment resulted in yield similar to the CK treatment, indicating that ADF could maintain tomato yield with a 40% saving in water use.  Based on the distribution of water and N, and tomato yield, a fertigation frequency of 6 days under ADF should be considered as a water-saving strategy for greenhouse tomato production.     

MODELING GROWTH AND ION CONCENTRATION OF LILIUM IN RESPONSE TO NITROGEN:POTASSIUM:CALCIUM MIXTURE SOLUTIONS

Nutrient solution composition plays an important role in root uptake rate due to interactions among nutrients and internal regulation. Studies to determine the optimum nutrient solution concentration are focused on individual ions, ignoring the adaptation mechanisms triggered by plants when growing in a varying external nutrient concentration. The objective of the present study was to determine the response in growth and tissue ion concentration of lilium cv. ‘Navona’ to nutrient mixtures of varying proportions of nitrogen (N), potassium (K⁺), and calcium (Ca²⁺) in solution using mixture experiments methodology in order to determine the optimum concentration. Bulbs of lilium were transplanted in plastic crates and drip-irrigated with the treatment solutions, which consisted of a mixture of N, K⁺, and Ca²⁺ whose total concentration was 340 mg L^?1 and minimum concentrations of each ion was 34 mg L^?1. Chlorophyll concentration (SPAD), shoot fresh weight (FW), leaf FW, and leaf area were measured 60 days after transplanting and ion analysis was performed on shoot tissues from selected treatments. Lilium exhibited a moderate demand for N and K⁺ (136–170 mg L^?1 N and 116–136 mg L^?1 K⁺) and a very low demand for Ca²⁺ (34–88 mg · L^?1). This low demand may be due to the remobilization of the nutrients stored in the bulbs. Integrating the predictions of the models estimated to produce >90% of maximum growth, the optimum nutrient solution should contain Ca²⁺ at a concentration between 34 and 126 mg · L^?1, K⁺ between 119 and 211 mg · L^?1, and N between 92 mg · L^?1 and 211 mg · L^?1. Increasing external N concentration affected internal N concentration but not internal K⁺ or Ca²⁺ concentrations, despite that the increase in external N was associated with a decrease in external K⁺ and Ca²⁺. Similar trends were observed for external K⁺ and Ca²⁺ concentration. In conclusion, lilium was able to maintain a relatively constant K⁺ and Ca²⁺ concentration regardless of the lower concentration in the nutrient solution when N was increased (similar response was observed for K⁺ and Ca²⁺) and it has a low Ca²⁺ demand and moderate N and K⁺ supply.     

设施土壤有机氮组分及番茄产量对水氮调控的响应

【目的】酸解铵态氮和酸解氨基酸氮是土壤有机氮的主要组分,可表征土壤的供氮能力,并在氮素矿化、固定、迁移以及为植物生长供氮过程中起到至关重要的作用。研究水、氮调控下设施土壤有机氮组分和番茄产量的相互关系,为评价设施土壤肥力变化和制定科学合理的水、氮管理措施提供科学依据。【方法】田间定位试验在沈阳农业大学的温室内进行了5年,供试作物为番茄,栽培垄上覆盖薄膜,打孔移栽番茄幼苗,膜下滴灌。定位试验三个氮肥处理为施N75、300、525kg/hm^2,记为N1、N2和N3;三个灌水量为25、35和45kPa灌水下限(灌水始点土壤水吸力),记为W1、W2和W3,共9个肥水处理组合。在试验第五年番茄生长期(2016年4—8月)调查了番茄产量及其构成,在休闲期(2016年9月)测定0—10、10—20和20—30cm土层土壤有机氮组分、有机碳和全氮含量。【结果】9个处理中,土壤全氮、有机碳和除酸解氨基糖氮外的有机氮组分含量均随土层深度的增加而降低,且0—10、10—20和20—30cm土层间含量差异显著(P<0.05)。三个土层中酸解总氮占土壤全氮的66.0%、64.6%和55.2%,是土壤有机氮的主要存在形态。土壤酸解总氮中各组分含量及其所占比例的大小顺序为酸解氨基酸氮、酸解铵态氮>酸解未知态氮>酸解氨基糖氮。灌水下限和施氮量对番茄产量及单果重的影响均达极显著水平(P<0.01),水氮交互效应也达显著水平(P<0.05)。休闲期土壤酸解铵态氮与番茄产量间显著负相关(P<0.05)。番茄产量W1N2(25kPa+N300kg/hm^2)、W2N1(35kPa+N75kg/hm^2)和W1N1(25kPa+75kg/hm^2)处理间差异不显著。【结论】灌水和施氮量及其交互效应对各土层土壤全氮、酸解总氮、酸解铵态氮和酸解氨基酸氮的影响均达到极显著水平(P<0.01),而对土壤有机碳的影响不显著(P>0.05)。相同施氮量下,0—30cm土层酸解铵态氮和0—20cm土层酸解氨基酸氮含量均在土壤水吸力维持在35~6kPa范围内达最高值,此土壤水分含量下的0—20cm土层酸解氨基酸氮含量在施N75kg/hm^2时达到最大值。从节水减氮和番茄产量的角度考虑,控制土壤水吸力不低于35kPa、每季随水施N75kg/hm^2为供试番茄生产条件下最佳的水、氮组合量。