沼液化肥配施对芦笋地土壤肥力及芦笋品质的影响

针对芦笋种植过程中大量化肥长期施用所造成的土壤肥力退化和芦笋品质下降的问题，以沼液有机替代化肥来研究相同氮磷钾养分施用的前提下，沼液不同用量替代化肥施用对芦笋地土壤肥力及芦笋品质的影响。试验设不施肥处理（CK）、常规施肥处理（NPK）、沼液全氮替代化肥施氮质量25%、50%、75%和100%的处理，共6个处理，分析了沼液替代化肥施用条件下，沼液不同用量对土壤理化性质、微生物量、酶活性、重金属含量及芦笋品质的影响。结果表明：与常规施肥（NPK）处理相比，沼液替代化肥用量≥50%的处理显著增加了土壤有机质的质量分数32.7%～41.5% （P<0.05），但其对土壤全氮、全磷和全钾质量分数无显著影响（P>0.05）；同时，沼液替代量75%和100%的处理显著提高土壤pH值0.72和1.0，并显著提高土壤速效钾质量分数48.6%和48.8%（P<0.05），而其对土壤碱解氮和有效磷质量分数没有显著影响（P>0.05）。与不施肥（CK）处理相比，常规施肥、沼液替代化肥施用各处理均能增加土壤蔗糖酶的活性，但沼液替代化肥用量≥50%的处理均显著降低了土壤酸性磷酸酶的活性（P<0.05），而对土壤脲酶和过氧化氢酶活性影响均不显著。与NPK处理相比，沼液替代化肥施用显著提高了土壤微生物生物量碳和氮的含量20.2%～61.2%和28.8%～162.0%（P<0.05），但沼液替代量≥50%处理的土壤微生物碳/氮比值与NPK处理相比都显著降低了31.4%～38.6% （P<0.05）。常规施肥、沼液替代化肥施用对芦笋地表层土壤重金属Cu、Cr、Cd、Ni、Pb和Zn的含量均无显著影响。与NPK处理相比，75%和100%沼液替代化肥处理芦笋嫩茎中显著增加了可溶性蛋白含量111.1%和155.6%，并显著提高微量元素Zn的含量27.8%和30.0%（P<0.05）。可见，沼液替代化肥施用能够显著提高芦笋地土壤有机质和速效养分的含量，促进芦笋地土壤肥力水平的提高，以及芦笋可溶性蛋白和Zn含量的提高，优化芦笋品质，其中以沼液替代量≥75%效果较好。可见，沼液化肥配施能够提升土壤肥力水平，促进芦笋品质的提高。

Effects of the combined biogas slurry with chemical fertilizer on soil fertility and Asparagus quality in field

Soil fertility degradation can be attributed to a large amount of chemical fertilizer in the long term. Among them, the quality of asparagus shoots can depend mainly on the soil fertility in the process of asparagus planting. This study aims to investigate the effects of biogas slurry application with the chemical fertilizer on the soil fertility in the asparagus field. The quality of asparagus shoots was also evaluated in the same application of nitrogen, phosphorus, and potassium nutrients. Six treatments were set, including no fertilization (CK), conventional fertilization (NPK), the total nitrogen of biogas slurry replaced 25%, 50%, 75%, and 100% of the total nitrogen application amount of chemical fertilizer (25%NP1K1Z1, 50% NP2K2Z2, 75% NP3K3Z3, and 100% NP4K4Z4). Some influencing factors were selected, including the amount of biogas slurry application on the soil''s chemical properties, enzyme activities, microbial biomass, and heavy metals in the asparagus field. The results showed that the soil organic matter contents increased by 32.7%-41.5% in the 50% NP2K2Z2 treatment, compared with the NPK (P<0.05). But there was no significant effect on the contents of soil total nitrogen, total phosphorus, and potassium (P>0.05). At the same time, the 75% NP3K3Z3 and 100% NP4K4Z4 treatments were significantly improved the contents of soil available potassium by 48.6% and 48.8%, while also significantly improved improving pH value by 15.2% and 21.1% (P<0.05), but there was no significant influence on the contents of soil alkali hydrolyzed nitrogen and available phosphorus (P>0.05). Comparison In comparison with the CK, the 50% NP2K2Z2 treatment was significantly reduced the activity of soil acid phosphatase (P<0.05), but there was no significant effect on the soil urease and catalase activities. By contrast, the rest treatments were enhanced the activity of soil sucrose enzyme. Compared with the NPK, the ratio of carbon and nitrogen of soil microbial biomass was significantly reduced by 31.4%-38.6% in the 50% NP2K2Z2 treatment (P<0.05). But, there was the a significant increase in the carbon and nitrogen contents of soil microbial biomass by 20.2%-61.2%, and 28.8%-162.0%, respectively (P<0.05) in the rest treatments. All treatments presented the little effect on the contents of Cu, Cr, Cd, Ni, Pb, and Zn in the topsoil of the asparagus field (P>0.05). In addition, the 50% NP2K2Z2, and 75% NP3K3Z3 treatments were improved the Zn contents and soluble protein contents in the tender stem of asparagus, compared with the NPK (P<0.05). Thus, the soil organic matter and available nutrients were improved for the soil fertility in the asparagus field. As such, the soluble protein and zinc contents were enhanced the quality of the tender stem of asparagus. Among them, the optimal treatment was achieved in the 75% NP3K3Z3 with the amount of total nitrogen of biogas slurry replaced by more than 75% of the total nitrogen application amount of chemical fertilizer.