Recovery of phosphorus fertilizer in potato as affected by application strategy and soil type

Phosphorus (P) fertilizers are usually supplied prior to or at planting of potato even though most P is taken up 40 to 80 d after emergence. This may lead to inefficient P use as a result of P leaching or fixation in the soil. This study evaluates the effects of split P application at multiple times during the growth period according to the plant's need for P. Potato (Solanum tuberosum L. cv. Ditta) was grown in pots in climate chambers, and radioactive ³²P isotope was used to distinguish between the fertilizer and soil‐derived P sources. Two soils were tested in combination with five application rates of P, and the plants were harvested at four dates. The results show that the recovery of P fertilizer can be significantly enhanced if the P supply is split. The result also showed that the proportion of soil‐derived P, accumulated in the plant, was significantly reduced both when more fertilizer P was applied to the soil and when P supply was split into several applications. The positive effects of multiple P applications on the P recovery were greatest in the soil with low P status and low buffer capacity.     

Mixed Fertilizer can Improve Fruit Yield and Quality of Field-Grown Tomatoes Irrigated with Saline Water

Growing tomatoes using saline water and in soils with poor nutrient contents is challenging. The objectives of this work were to: (i) examine the yield and quality of tomatoes (Lycopersicon esculentum L.) irrigated with different saline water [electrical conductivity (ECi) = 3, 6 and 9 dS m^?1]; and (ii) study the effect of fertilizer: inorganic, organic, and a mixed of both on tomatoes grown under saline conditions. Fruit weight and quality attributes including size, color, soluble solids, acidity, EC, and pH were measured. Growing tomatoes under 3 and 6 dS m^?1 produced the highest yield, whereas irrigating with 9 dS m^?1 reduced yield. The mixed fertilizer slightly ameliorated the yield reduction caused by salinity. Using organic fertilizer alone produced the lowest fruit yield. Fruit quality was more affected by salinity than fertilizer. The best growing conditions for tomatoes were in plots irrigated with 6 dS m^?1 water under mixed fertilizer treatment.     

水氮耦合对滁菊产量和品质的影响

采用二因素二次回归旋转组合设计,以盆栽试验方式研究了水、氮因子对滁菊产量和品质的影响,探讨了滁菊人工栽培适宜的水氮管理模式。研究结果表明,水氮耦合对滁菊花产量、叶片水提总黄酮和氯原酸含量、滁菊花水提总黄酮和氯原酸含量均有极显著影响,水氮间存在显著交互作用。氮肥因子对滁菊花产量、总黄酮含量、氯原酸含量的影响大于水分因子。当土壤水分水平为0.284 1,氮肥水平为0.403 7时,即田间持水量80%,氮肥用量0.257g/kg时,滁菊花产量最高,达18.09g/株;当土壤水分和氮肥用量均为-1.414水平时,即田间持水量50%,氮肥用量为0g/kg时,滁菊花总黄酮含量和氯原酸含量最大。从滁菊花产量、品质角度综合考虑,滁菊生育前期水氮管理以中水中氮较为适宜,滁菊现蕾开花期以低水低氮较为适宜。     

保水剂与磷肥的相互影响及节水保肥效果

采用茶袋法测定保水剂在磷酸一铵、过磷酸钙溶液中的吸水倍率,并以差减法计算保水剂对磷素养分的吸持量,研究不同磷肥对保水剂吸水性能以及保水剂对不同磷肥的吸持作用的影响;盆栽条件下以玉米为供试作物,研究保水剂和不同磷肥配合施用下的节水保肥效果。结果表明:保水剂在不同磷肥溶液中的吸水倍率随肥料浓度的增加而下降,过磷酸钙对保水剂吸水倍率的影响大于磷酸一铵;保水剂在大量吸水的同时,也对溶于水中的磷素养分有吸持作用,吸持量随肥料浓度的增加出现先增大后减小的规律;保水剂和磷肥配合施用能增加叶片净光合速率和气孔导度,提高玉米生物量和水肥利用效率,保水剂与磷酸一铵配合施用水肥调控效果较好。     

耕层厚度对潮土中化肥氮素转化的影响

耕层厚度是影响土壤肥力的重要因素之一,但其对潮土中化肥氮素转化的影响尚不清楚。利用田间?土柱模拟试验,采用15N示踪技术,探究在不同耕层厚度处理下,化肥氮在3种质地潮土0~40 cm土层中有机氮、无机氮与固定态铵库中的动态变化以及作物对化肥氮的吸收利用。结果表明：耕层厚度显著影响化肥氮在土壤不同氮库中的转化及其在土壤-作物系统中的去向,且在不同质地潮土中的作用效果一致。在不同质地潮土中,残留于土壤中的化肥氮83%以上以有机氮的形式存在,影响化肥氮的保蓄与供给。增加耕层厚度虽然降低了化肥氮向固定态铵库的转化,但提高了0~40 cm土层中的肥料来源有机氮储量,尤其是在施肥当季,耕层厚度25 cm（PLT-25）处理下的肥料来源有机氮储量平均较耕层厚度15 cm（PLT-15）处理提高8.9%。增加耕层厚度显著（P < 0.05）提高了施肥当季与后茬作物生长季内肥料来源无机氮的供给,在此期间PLT-25处理下作物对化肥氮的利用率较PLT-15处理提高8.0%左右,而化肥氮的当季损失率与累积损失率则较PLT-15处理分别降低12.3%与9.1%。就土壤质地的角度而言,砂粒含量高制约着化肥氮向有机氮库的转化,不利于作物对化肥氮的吸收利用,增大了氮肥损失。由此可见,在不同质地潮土中,增加耕层厚度在提高化肥氮素当季利用率的同时也增大了化肥氮在土壤中的残留量,减少了化肥氮的损失。残留的化肥氮在后茬作物生长季释放出来供作物吸收利用,促进了化肥氮累积利用率的提高。     

肥液浓度对单膜孔入渗NO-3-N运移特性影响的室内试验研究

该文通过室内入渗试验，研究了不同浓度的单膜孔肥液入渗NO^-₃-N的分布特性。研究表明：不同浓度的膜孔肥液入渗土壤NO^-₃-N浓度的湿润锋运移距离与土壤水分运动的湿润锋一致；肥液浓度越大，相同入渗时间的NO^-₃-N浓度锋运移距离越大，土壤剖面NO^-₃-N浓度最大值越大，相同深度处土壤NO^-₃-N浓度也越大。肥液入渗土壤NO^-₃-N浓度分布特征与湿润体深度符合分段函数模型。供水入渗过程中，NO^-₃-N浓度锋运移距离和浓度最大值均随时间的延长而增大；再分布过程中，NO^-₃-N浓度锋运移距离继续增大，而NO^-₃-N浓度最大值逐渐减小。     

Co-amelioration of red soil acidity and fertility with pig manure rather than liming

Lime (calcium oxide), animal manure and crop straw soil treatments have been shown to ameliorate soil acidity, yet their effectiveness at concurrently enhancing soil fertility status and improving crop yields is less well understood. In this study, an acidic nutrient deficient red soil (Ferralic Cambisol) received these treatments at various dosage rates (% of DW soil) in pot experiments with maize plants. Lime was applied at four dosage rates (0.05%, 0.10%, 0.15% and 0.20%), pig manure at three rates (0.50%, 1.00% and 1.50%), maize straw or milk vetch at two rates (0.50% and 1.00%) and combinations of lime (0.10% or 0.15%) with maize straw (0.50%) and/or pig manure (0.50%). Soils treated with and without chemical fertilizers were also included as controls. Measurements of soil pH, exchangeable acidity, plant available nutrients and maize shoot biomass were recorded. Maize shoot biomass increased by 4.7–7.6 times under pig manure treatments, 1.1–1.6 times under milk vetch, 0.4–1.5 times under lime and 1.1–6.2 times under combination treatments, compared with the control. Soil pH increased by 0.5–0.9 units under lime, by 0.2–0.4 units under pig manure and by 0.7 pH units under the combination treatment relative to the control. Variance partitioning analysis showed that on an individual basis, soil acidity amelioration (pH, exchangeable H⁺ and Al³⁺) or nutrient input (C, N, P, K, Ca, Mg, Zn) explained only 4.3% and 5.6% of improved maize growth, respectively. Whereas, their interaction explained 85.9% of the variation. We also report that the over-application of pig manure could lead to P saturation and negative impacts on aquatic systems in the wider environment. Therefore, we recommend a combination of lime, pig manure and straw provides an optimal solution for addressing soil acidity and limiting P saturation in acid soils.     

Biochar derived from dairy cattle carcasses as an alternative source of phosphorus and amendment for soil acidity

Two pot experiments were conducted to evaluate biochar derived from dead dairy cattle as a mineral fertilizer, especially phosphorus (P) fertilizer, and to clarify the effect of particle size of biochar on plant growth (Zea mays L.) and P uptake. To produce the biochar, body parts of dead cattle were placed in a charring chamber and allowed to char at 450°C for 4 h. The biochar was of high pH and rich in major plant nutrients, especially P. Application of fine biochar (< 1 mm) increased P uptake by the corn plants grown in soil of low available P status. As a result, plant growth was improved following biochar application and dry matter production was also increased. The effect of the biochar application on the P uptake and plant growth was promoted by the application of mineral nitrogen (N) fertilizer. Soil analysis after harvest indicated that the biochar application increased soil pH, available P and exchangeable calcium (Ca) and magnesium (Mg) compared with the soil before seeding, while soil available N and exchangeable potassium (K) were considerably decreased. The decrease in the soil available N was incomprehensible, because the result of the mass balance given by the difference between input as the applied N from the biochar and fertilizer N and output as the N uptake by the plants was positive. We observed a similar result in the mass balance of K to the case of N. The medium (2–4 mm) and coarse (> 4 mm) grade biochar did not significantly affect plant growth, because P uptake was not, or was only slightly, increased by the application of these biochars. Dissolution of P from the coarser biochars was probably slower than that of the fine biochar. The lower dissolution of P from the medium and coarse biochars was supported by the lower P absorption efficiency of these biochars compared with that of the fine biochar and superphosphate. The effect of fine biochar on plant growth and P uptake was similar to that of superphosphate. We can therefore conclude that fine biochar derived from cattle carcasses is an effective source of P fertilizer and amendment for soil acidity. The N and K contents in the biochar, although relatively high, cannot be relied upon as a mineral fertilizer. Further studies are needed to assess whether the N and K contents of the biochar indicate it can be regarded as a useful fertilizer.     

矿物包裹型缓释肥料肥效研究

采用微区试验方法,对小试生产的矿物包裹型缓释复合肥料进行了肥效研究.结果表明,缓释肥料与等养分量的复合肥料相比,黑麦草的干物质累积量显著增加,增幅为6.4;～8.1;,缓释肥料的肥效期明显延长、肥料增产效率明显提高.     

京9428小麦施肥量和氮素化肥不同施肥比例试验研究

本文是关于小麦京9428品种不同施肥量和氮素施肥比例对产量、群体动态的试验研究。结果表明:氮、磷、钾比例为16︰9︰6的处理京9428小麦群体动态表现好,667m2产量最高,667m2产达351.4kg,667m2效益最大;氮素化肥底、追施比例为5︰5的处理生长发育好于7︰3的处理;产量也相对表现较好。可见小麦京9428中后期对氮素营养需求很关键,应加强对小麦中期的肥水管理,保证氮素营养的供应。