【作者】 唐政；

【导师】 邱建军；

【作者基本信息】 中国农业科学院 ， 作物生态学， 2009， 博士

【摘要】 本研究针对有机蔬菜生产中由于不合理灌溉和施肥而导致的蔬菜品质下降、环境污染风险提高等问题,以北京郊区典型保护地有机蔬菜种植为对象,按照当地种植习惯的小油菜-香菜-番茄-黄瓜轮作体系,通过4茬的田间定位试验,研究不同水肥管理方式下蔬菜产量、品质的差异,施用有机肥对氮、磷、钾在土壤中的累积和分布动态的影响,以及由此带来的重金属威胁,并利用自流式农田地下淋溶收集装置揭示蔬菜地水分渗漏和有机肥中无机氮的淋洗特征,探讨有机种植氮素在土壤-作物体系中分配与表观平衡规律。主要结果如下:(1)有机肥不同施用量随栽培时间而逐步影响蔬菜产量。在小油菜-香菜-番茄-黄瓜轮作体系中,常规施肥处理的N/P2O5/K2O达到2.08/1.6/0.7(t/ha)。随种植年限的延长,常规施肥处理相对于减半量施肥处理的产量优势逐渐明显。由于基础肥力过高,不同水肥管理间头两茬小油菜、香菜产量差别不显著;常规施肥番茄产量比施肥量减半的稍高,但差异不显著;不同施肥量处理对黄瓜产量有显著影响。常规水肥管理方式下有机肥的利用率以及经济效益不如减半量施肥管理方式高。试验结果表明常规模式的有机肥投入过多,在常规施肥的基础上施肥量减半是可行的。(2)有机肥过量施用明显影响了蔬菜品质。除蔬菜Vc含量随施肥量递增外,在施肥量减半处理下,番茄红素含量、可溶性蛋白的含、可溶性糖类含量、可溶性固形物、糖酸比等营养品质和口感都优于常规水肥管理。有机肥用量过大使土壤中有较高的无机氮累积是造成蔬菜硝酸盐含量超标的主要原因,小油菜、香菜中的硝酸盐含量均严重超标;在随后的种植中,通过减半量施肥,有效降低了番茄、黄瓜硝酸盐含量。尽管有机肥和土壤中重金属含量都低于有机种植标准,但施有机肥后,番茄、黄瓜和土壤中镉(Cd)、铬(Cr)、铅(Pb)、汞(Hg)、砷(As)、铜(Cu)、锌(Zn)、镍(Ni)等八种重金属含量提高,并随施肥量的增加而上升。(3)有机肥过量施用造成大量养分在土壤中残留。常规施肥和减半量施肥对0-20cm和20-40cm土层磷素、钾素的累积均造成了显著性差异。常规施肥条件下,表层0-20cm速效磷的浓度超过400 mg/kg,0-40cm土体中磷的累积超过1300 kg/ha,表层0-20cm的速效钾浓度超过300 mg/kg,0-40cm土体中钾的累积超过1400 kg/ha。(4)过量施用有机肥是造成无机氮表观平衡值增加。土体中过剩的无机氮主要以硝态氮的形式存在;常规施肥造成无机氮在0-20cm土层中大量残留,常规灌溉和减量灌溉下分别为430.23 kg/ha和410.12 kg/ha,减半量施肥在常规和减量灌溉下分别为297.99 kg/ha和205.96 kg/ha,显著降低了无机氮的残留。在表层大量残留的无机氮在短时期内向60cm以下的土层没有出现明显迁移,60cm以下的土层中无机氮含量的变化幅度很小。常规施肥处理造成0-90cm土体的无机氮表观平衡值超过1400 kg/ha,减半量施肥处理下的无机氮表观平衡值可下降到450.49kg/ha。在常规施肥量的基础上施肥量减半能在保证氮素供应的前提下较好地维持氮素表观平衡。(5)灌溉量过大是造成氮素淋失的最重要因素。在较短时期内,灌溉相比施肥而言,对氮素淋失的影响更大,控制灌溉量比控制施肥量更能减少氮素淋溶损失。常规和减量灌溉下不施肥造成的氮素累积淋失量分别为36.07 kg/ha、27.05 kg/ha;常规水肥管理下氮素淋失量为59.8 kg/ha,施肥量减半可使氮素淋失减少14.51 kg/ha;而减少1/3灌溉量可使氮素淋失减少17.89 kg/ha,水肥同时减量则可减少25.43 kg/ha。在常规灌溉条件下,常规施肥和减半施肥处理下有机肥的淋失率分别为1.18%和0.88%;减量灌溉条件下分别为0.74%和0.8%。(6)长期、大量施用有机肥容易产生土壤重金属累积。本试验的有机肥中重金属含量较低,在短时期内还没有出现重金属污染问题。施肥条件下,常规水肥处理下的蚯蚓数量最多,达46只/m3,高于其他各施肥处理但没有达到显著差异水平。更多还原

【Abstract】 This paper aimed at the problems, such as vegetables quality decline, the risk of environment pollution risk increasing and so on, which induced by irrational irrigation and excessive fertilizer application during vegetables production. A field experiment was carried out to study the effects of irrigation and organic manure application on yield and quality of vegetables, accumulation and distribution of N, P, K in soils, and heavy metal potential pollution in small rape-caraway-tomato-cucumber rotation system based on the traditional way used by local farmers. Meanwhile, the lysimeter method was used to study the characters of water leakage and nitrate leaching from organic fertilizer in vegetable fields, and the distribution and apparent balance of N in soil-plant systems. The results were as follows:(1) For small rape - caraway - tomato - cucumber rotation system, the content ratio of N/P2O5/K2O was 2.08/1.6/0.7 (t/ha) in conventional fertilization treatment. Gradually, manure application rate affected vegetable yields during cultivation time. Compared with the half conventional fertilizer treatments, the yield had great advantages in conventional fertilizer treatments. There was no significant water and fertilizer effect on yields of small rape and caraway under. The tomato yield in conventional fertilizer treatment was higher than that in half conventional fertilizer treatment, but the difference did not reach significant level. There was a significant effect of fertilizer application rates on cucumber yields. However, the use efficiency of organic fertilizer and economic benefit under conventional water and fertilizer management system were lower than that of the half conventional water and fertilizer management system. The experimental results showed that the input rate of organic manure was excessive under conventional water and fertilizer management, and so the half conventional organic manure input was feasible.(2) In addition to Vc content in vegetables was increasing with the fertilizer application rates, the taste and quality of nutrition under half conventional fertilizer input treatment, such as the lycopene content, soluble protein content, soluble sugar content, soluble solids, sugar and acid ratio and so on, were all superior to conventional water and fertilizer treatment. Excessive use of organic fertilizers resulted in high accumulation of inorganic nitrogen in soils, which was the main cause for over-standard of the nitrate content in vegetables. Half of the fertilizer application decreased nitrate contents in tomato and cucumber. Organic fertilizer application rate impacted on the content of heavy metals in tomato. The contents of heavy metals, such as cadmium (Cd), chromium (Cr), plumbum (Pb), mercury (Hg), arsenic (As), copper (Cu), zinc (Zn), nickel (Ni), increased in tomato, cucumber and soils, there a increasing trend of the contents with the increase of the organic fertilizer application rates.(3) The nutrient inputs far exceeded the crop uptakes in this systems, which resulting in a large number of nutrients accumulating in soils. Both fertilizer application and half conventional fertilization resulted in significant differences of available P and K content in 0-20 cm and 20-40 cm of soil layers, especially for the conventional fertilizer treatment, the accumulation of P and K increased rapidly. The concentration of available P in the conventional fertilizer treatments in the 0-20 cm soil layer was above 400 mg/kg and over 300 kg/ha for available K.(4) Fertilizer application was the main reason that increasing the inorganic N apparent balance. The mainly form of the residual inorganic N in soils was NO3--N. Conventional fertilizer application resulted in a large number of inorganic N accumulating in 0-20cm soil layer. The inorganic N in in conventional irrigation and reduction of irrigation were 430.23 kg/ha and 410.12 kg/ha, and 297.99 kg/ha and 205.96 kg / ha in half conventional fertilizer application, respectively, a significant reduction in residues of inorganic N. A large number of residual inorganic N in soil surface did not transfer to 60cm below soil surface. The inorganic N content in 60cm below soil surface changed slightly. Conventional fertilizer application resulted in inorganic N apparent balance value over 1400 kg/ha in 0-90 cm soils, which will be reduced to 450.49kg/ha in half the amount of fertilizer treatments. Half of fertilizer application can maintain the apparent N balance well under ensuring the N supply.(5) Irrigation is a key factor influencing soil N leaching. In a short period of time, the effects of irrigation on N leaching were greater than fertilizer application. So compared with control fertilizer application treatment, control irrigation was more effective to reduce loss of N leaching. Traditional and half traditional irrigation without fertilizer application resulted N leaching 36.07 kg/ha, 27.05 kg/ha, respectively. The N leaching in traditional irrigation and fertilizer application treatments was 59.8 kg/ha, and was decreased by 14.51, 17.89 and 25.43 kg/ha in half input of fertilizer, 2/3 of traditional irrigation, and the reduction of water and fertilizer treatments. In the traditional irrigation condition, the N leaching loss rates were 1.18% and 0.88% in traditional manure treatment and half traditional manure treatments, respectively. In the half traditional irrigation condition, the N leaching loss rates were 0.74% and 0.8% in traditional manure treatment and half traditional manure treatments.(6) Long-term, a large number of organic manure applications will lead to the accumulation of heavy metals in soils. The content of heavy metals in the organic fertilizer was low in this study, and it had not yet appeared heavy metal pollution in a short period of time.The number of earthworms was the largest in the conventional water and fertilizer management treatment, and was 46 m-2 that higher than other treatments. However, the difference was not significant.更多还原