冀中地区桃树优质高产的叶片氮磷钾临界值范围及化肥投入量

【目的】研究叶片养分含量与产量、品质的关系,并依据该关系确定冀中地区桃树优质高产的叶片氮磷钾临界值范围,及实现该目标所需的化肥投入量与土壤养分保证量。【方法】在冀中地区选取60个小型桃园进行了连续3年的跟踪监测。于盛花期后60天采集桃树叶样,测定氮磷钾含量。收获后,调查果实产量、单果重和可溶性固形物含量(SSC),将各指标分为4个等级。采用单因素方差分析法和边界线分析法,探讨叶片养分含量与3个生产目标的关系,并以产量、品质的最高等级标准对应的叶片养分含量适宜范围与土壤速效养分含量、施肥量进行边界线分析,确定实现优质高产目标的所需的化肥投入量及土壤速效养分含量的保证量。【结果】按照产量、单果重和可溶性固形物含量水平,将桃园等分为4组。随着桃园产量、品质等级的提高,叶片养分含量的变异逐渐减小,等级最高桃园的叶片养分含量多处于居中水平,且分布较集中,变异范围较窄。3个生产目标的叶片全氮、全磷、全钾边界值分布均呈现极显著的抛物线形。基于边界线方程,叶片全氮、全磷、全钾高产目标(>45 t/hm2)下的适宜范围分别为3.33%~4.12%、0.16%~0.29%和1.54%~2.50%;大果目标(>350 g/个)的适宜范围分别为3.05%~4.61%、0.13%~0.35%和1.45%~2.57%;甜度目标(SSC>15%)下分别为3.30%~4.09%、0.17%~0.32%和1.59%~2.64%;同时满足优质高产的叶片全氮、全磷、全钾综合指标范围分别为3.33%~4.09%、0.17%~0.29%和1.59%~2.50%。盛花期后60天叶片全氮、全磷、全钾的临界值可与前期化肥N、P2O5投入量及土壤速效钾含量做出显著的边界线模型,且均呈直线加平台关系。化肥N、P2O5投入量及土壤速效钾含量的拐点分别为210.2 kg/hm2、236.3 kg/hm2和110.2 mg/kg,保证叶片适宜的氮磷钾养分含量需要投入的氮肥和磷肥量分别为N 40.2~166.8 kg/hm2、P2O5 11.3~161.3 kg/hm2,钾素则需要土壤速效钾含量达到36.3~86.8 mg/kg。【结论】综合考虑果实产量、个体大小和甜度,盛花期后60天叶片氮磷钾临界值范围分别为3.33%~4.09%、0.17%~0.29%和1.59%~2.50%,满足叶片氮、磷含量可通过施用N40.2~166.8 kg/hm2、P2O5 11.3~161.3 kg/hm2来实现,而满足叶片钾含量则需要保证土壤速效钾含量在36.3~86.8 mg/kg。

湖南洞口县猪粪基质养殖蚯蚓以及蚯蚓土壤种植黑麦草测产试验

在洞口县杨林镇进行猪粪基质养殖蚯蚓和蚯蚓土壤种植黑麦草测产试验。试验结果:1) 养殖蚯蚓试验:60天猪粪基质pH 8.77,碱解氮0.71 g/kg,有效磷1.02 g/kg,速效钾1.92 g/kg,有机质22.32%,有效活菌数量5.21 × 108个/g。90天猪粪基质pH 8.87,碱解氮0.58 g/kg,有效磷0.91 g/kg,速效钾1.73 g/kg,有机质20.93%,有效活菌数量5.14 × 108个/g。60天猪粪基质比90天猪粪基质分别减少1.1%、增加22.4%、12.1%、11.0% (这3项差异显著P 2黑麦草鲜草最高产量达24,811 kg,较对照组(一般土壤种植)增产10,738 kg,增产76.3%,1 kg猪粪基质增产黑麦草鲜草10.47 kg。试验II组(90天猪粪基质)每667 m2黑麦草鲜草产量22,147 kg,较对照组增产8074 kg,增产57.4%,每667 m2施入猪粪基质1025 kg,1 kg猪粪基质增产黑麦草7.88 kg。60天猪粪基质较90天猪粪基质种植的黑麦草的产量高12.1%。结论:养殖蚯蚓60天猪粪基质较90天猪粪基质肥力高,其土壤种植的黑麦草的产量也高。并对培养蚯蚓土壤、蚯蚓改良修复土壤作用机理和用途进行了有益探索,为农业同行养殖蚯蚓和蚯蚓土壤利用方面提供参考。

Interaction of NPK Fertilizers During Their Transformation in Soils: I. Dynamic Changes of Soil pH

Dynamic changes of soil pH as influenced by ammonium sulfate (AS),monocalciuin phosphate (MCP), potassium chloride (KCl) and their interaction in soils were evaluatedin incubation experiments. Applying these fertilizers significantly reduced soil pH values in allcases and followed sequences of AS > MCP > KCl, MCP > KCl > AS and KCl > AS > MCP for the paddy,calcareous and red soils, respectively. The AS-induced reduction of pH in the three soils followedthe sequence of red soil > paddy soil > calcareous soil, while in MCP and KCl systems the reductionof pH followed the sequences of calcareous soil > paddy soil > red soil and red soil > calcareoussoil > paddy soil, respectively. The interactions of the NPK fertilizers on pH were significant. MCPplus KCl or MCP plus AS reduced pH values more than the fertilizers applied solely in the paddysoil, but AS partly counteracted the effect of MCP on pH in the 1 d sample of the calcareous soil.The effect of MCP on pH was trivial when MCP was applied in combination with KCl or AS in the redsoil. When applied in combination with AS, KCl did not affect soil pH initially, but suppressed thereduction of pH at the later incubation stage, which was related to inhibition of nitrification byKCl in the soils.

Characteristics of Magnesium Release from Fluvo-Aquic Soil and Relative Availability of Magnesium to Plants

Experiments including two in laboratory and one in greenhouse were carried out to study non- exchangeable magnesium release from fluvo-aquic soils sampled from Daxing and changping counties located in the suburbs of Beijing and Mg relative availability of the two soils to plants. In a batch experiment in laboratory the soils were incubated under wet conditions and alternation of dry and wet conditions and determined for amount of Mg released at the 4th, 8th and 12th week, respectively, after extraction of exchangeable Mg with 1 mol L-1 NH4Ac. The amount of Mg released from the soil of Daxing was higher than from the soil of Changping, which was in accordance with the fact that the soil of Daxing had higher contents of all forms of Mg than that of Changping. There was little difference in Mg release from soils between wet conditions and alternation of dry and wet conditions. About 1%~2% of the total non-exchangeable Mg might be released within 12 weeks of incubation, restoring about 30%~35% of the original soil exchangeable Mg. Results of the experiment on kinetics of Mg release from the soils through continuous extractions with 0.5 mol L-1 NH4Ac (pH 7.0) on a continuous flow apparatus in laboratory showed that Mg released rapidly in the beginning, decreased sharply with time and kept stable at 60 and 240 min for the soils of Changping and Daxing, respectively. Among the five mathematical models used to describe the kinetics of Mg release, the parabolic diffusion equation best fitted the cumulative Mg release, indicating that diffusion of Mg out of the soils might be the controlling process. The experiment of exhaustive cropping with 1 crop of tomato (Lycopersicon esculentum Mill.) followed by six crops of corn (Zea mays L.) in greenhouse showed that soil exchangeable Mg decreased remarkably with cropping. After three crops, the percentage of the total plant Mg uptake that came from soil non-exchangeable Mg was 29.5% for the soil from Changping and 35% for the soil from Daxing. About 50% of the total Mg uptake by plants in the six crops was believed to come from the soil non-exchangeable Mg form.