污泥及其混合堆肥对番茄土壤性质和N_2O排放的影响

目前关于污泥及其生物质堆肥的土地利用过程中土壤性质变化和温室气体排放数据十分缺乏,难以满足农田土壤氮素保存和温室气体减排的需求。该研究通过在番茄种植过程中添加800 kg/hm2新鲜污泥(S-H)、400 kg/hm2新鲜污泥(S-L)、800 kg/hm2秸秆堆肥(VM-S)和800 kg/hm2猪粪堆肥(VM-M),开展土壤性质、无机氮形态、作物生长以及N2O排放特征的研究。结果表明:堆肥处理显著增加了土壤电导率(electric conductivity,EC)(P0.05),其中猪粪堆肥时土壤EC值最大。添加污泥和堆肥都使土壤p H值显著上升(P0.05),最终趋于中性,且VM-M对土壤酸化的抑制效果略优于VM-S。污泥和堆肥处理时土壤NO3--N浓度显著高于对照,且各处理组NO3--N浓度均随时间逐渐下降,NO3--N主要被番茄吸收,部分NO3--N从土壤上层淋溶至下层;NH4+大多数被氧化为NO3-,部分NH4+被植物吸收。在施入的无机氮量相等情况下,VM-M、VM-S、S-H处理组中番茄地上部分生物量分别为1 515、1 383、1 103 g/株,株高分别为56.8、54.5、51.3 cm,对番茄生长的促进效果为VM-MVM-SS-H,而S-H比S-L多施入的氮肥对番茄生长并未起到明显促进作用(P0.05)。与对照相比,污泥或生物质堆肥都显著提高了土壤N2O的排放(P0.05),各处理组N2O的排放均集中于施肥后的前20天,且土壤N2O的排放通量大小顺序为S-L(0.76 kg/(hm2·a))VM-M(0.95 kg/(hm2·a))VM-S(1.19 kg/(hm2·a))S-H(1.71 kg/(hm2·a))。因此,在进行污泥及其生物质堆肥的土地利用时,应考虑有机肥的种类及其施用量,以在提高作物产量的同时改善土壤并减少温室气体排放,在进行污泥的农田利用时可先将污泥与畜禽粪堆肥。

Effect of sewage sludge and its mixed compost on soil properties and N2O emission from tomato soil

Abstract: There is still a great uncertainty of nitrogen conservation and greenhouse gas reduction from farmland soil due to lack of data of the soil properties change and greenhouse gas emissions from the land application of compost and sewage sludge. In this study, tomato plants were cultivated in the greenhouse in treatments of 1) 800 kg/hm2 fresh sludge (S-H), 2) 400 kg/hm2 fresh sludge (S-L), 3) 800 kg/hm2 straw composting product (VM-S), 4) 800 kg/hm2 swine manure composting product (VM-M), and 5) no fertilization (CK). The soil properties, inorganic nitrogen forms and N2O emission characteristics were investigated. The results showed that, compost treatments significantly increased the soil EC value (P<0.05), and the VM-M treatment exhibited the largest soil EC value. With the addition of sludge and compost products, soil pH value increased significantly (P<0.05) and soil pH tended to be neutral. The inhibitory effect of VM-M on soil acidification was better than VM-S. Under the treatments of sludge and compost, concentration of soil NO3--N was significantly higher (P < 0.05) than the CK, and the NO3--N concentration of each treatment decreased gradually with time. Most of the NO3--N was absorbed by tomato plants, and part of the nitrate was leached from the upper to the lower soil layers. Most of the NH4+ was oxidized to NO3--N, but some were absorbed by plants. With the application of organic nitrogen, the shoot biomass in the VM-M, VM-S and S-H treatment was 1 515, 1 383 and 1 103 g/plant, respectively, each corresponded with the plant height of 56.8, 54.5 and 51.3 cm, respectively. The positive effect of the treatment on the tomato growth was VM-M > VM-S > S-H. In addition, the excess application of organic nitrogen fertilizer from S-H compared to S-L did not promoted growth of tomato markedly (P>0.05). Compared with the CK, N2O emission from soil was significantly improved by sludge (P<0.05). The N2O emission from the all treatments were focused on the first 20 days after fertilization, and the amount of emission of soil N2O was S-L (0.76 kg/(hm2·a)) < VM-M (0.95 kg/(hm2·a)) < VM-S (1.19 kg/(hm2·a)) < S-H (1.71 kg/(hm2·a)). Therefore, the types and the amount of manure should be considered when the sludge or compost was applied in farmland, so that, the yield of crops can be improved and the emission of greenhouse gases could be reduced at the same time, and it's better to compost using sludge and animal manure.