烤烟烟叶的氮、钾含量与土壤氮、钾含量的相互关系及其平衡研究

通过对烤烟中期中部烟叶与土壤的大田调查,研究氮、钾含量及其平衡的相互关系,结果表明:(1)烟叶含氮量与土壤全氮、土壤碱解氮含量之间呈显著正相关,当土壤含氮量过高时,烟叶含氮量与土壤含氮量(全氮或碱解氮)的规律性不明显;(2)烟叶含钾量与土壤全钾、土壤速效钾含量呈显著的正相关;(3)烟叶氮/钾比与土壤全氮/全钾比、土壤碱解氮/速效钾比和土壤全钾含量呈显著的相关性。     

Changes in potassium availability and other soil properties due to soil ingestion by earthworms

An incubation experiment was conducted to study the changes that occur in potassium availability and other soil properties with ingestion of soil by earthworms. Two soils were used. Raumai soil with high non-exchangeable K and Milson soil with low non-exchangeable K were incubated with two species of earthworm, Aporrectodea caliginosa and Lumbricus rubellus, for 8 weeks. The casts and soil samples were analysed for exchangeable K, Ca, Mg, Na, and H, pH, organic C, and texture. The results indicated that in Raumai soil, the exchangeable K levels of the casts of both earthworm species were significantly higher than for the control soil, the effect being more marked for L. rubellus than for A. caliginosa. In Milson soil, the exchangeable K levels were significantly lower in the casts of both types of earthworm than in the control soil. The nitric acid-extractable K of the soil and casts was not markedly different for either soil type, but available non-exchangeable K values were significantly higher for the casts of L. rubellus from Milson soil than for the noningested Milson soil. In Raumai soil, the exchangeable Ca was higher in the casts of L. rubellus, exchangeable Mg and H were reduced, and exchangeable Na did not change markedly in the cast compared to the control soil. For Milson soil, the casts contained lower exchangeable Ca and H but higher Na and Mg than the control. The casts of both species of earthworm had significantly higher pH values for both soil types. There was no marked difference in the organic C content of the control soil and cast samples for Milson but a reduction in the casts of A. caliginosa for the Raumai soil. Finer fractions increased in the casts of both earthworm species in both soil types.     

大豆对钼与氮、磷、钾的吸收分配动态及相互关系的初步研究

大豆植株中其叶片的钼、氮、磷含量均高于茎杆、叶柄、繁殖器官高于营养器官。钾在整个生育期中都保持较高的水平,只是叶片中的含量低于其它器官。种子中的钼、氮、磷、钾含量都较高。大豆吸收钼及氮、磷、钾的数量因品种及各生育阶段而有差异,吸收量以结荚至鼓粒期为最多,鼓粒期以后,安农75—59的植株中氮、磷、钾吸收量明显下降,唯有钼还在继续吸收,而安激一号对钼及氮、磷、钾仍在吸收。大豆对钼与氮、磷、钾的吸收呈极显著的直线相关,尤其是钼与氮相关最明显。安农75—59亩产189.5kg,需要N素16.05kg,P_2O_54.25kg,K_2O8.43kg,微量元素Mo357.32mg。安激一号亩产214.5kg.需要N素18.00kg、P_2O_55.01kg、K_2O8.85kg、微量元素Mo449.57mg。安激一号的种子除糖、脂肪含量较低外,而氮、磷、钾、钼、维生素C的含量均高于安农75 59。     

磷钾肥配合施用对玉米产量及养分吸收的影响

通过田间定位试验研究了磷、钾肥配合施用对玉米产量和养分吸收的影响。结果表明:在施用氮肥的基础上,合理配施磷、钾肥促进了玉米的生长发育,改善了玉米的经济性状,显著提高了玉米的产量。三季玉米平均产量以处理P90K120(脚标数字为每公顷土壤施用P2O5、K2O的数量,单位为kg/hm2)最高,达到了4912.7kg/hm2。肥料效应方程表明,磷肥的增产效应大于钾肥,同时合理配施磷、钾肥有利于养分的协调供应,提高了玉米植株体内的养分含量和吸收量。     

基于MC—UVE的土壤碱解氮和速效钾近红外光谱检测

应用可见/短波近红外光谱分析测量土壤碱解氮和速效钾含量.为了提高该分析方法的预测精度,消除无信息建模变量对模型稳定性的影响,原始光谱平滑后采用蒙特卡罗无信息变量消除方法(MC-UVE)对土壤碱解氮和速效钾的建模变量进行筛选,应用偏最小二乘方法(PLS)建立校正模型.对于碱解氮模型,采用MC-UVE PLS方法,建模变量减少为210,相关系数和预测均方差分别为0.84和17.1 mg/kg.对于速效钾的预测模型,采用MC-UVE方法后,建模变量减少为150,模型的预测相关系数为0.76,预测均方根误差为15.4 mg/kg.     

Comparing the Nitrogen and Potassium Requirements of Canola and Wheat for Yield and Grain Quality

ABSTRACT

Grain yield increases (responses) of canola (oilseed rape, Brassica napus L.) and spring wheat (Triticum aestivum L.) to application of nitrogen (N) and potassium (K) fertilizers were compared in the same experiment at eight field sites over three years (2000–2002) in southwestern Australia. Four rates of N (0–138 kg N/ha as urea) and four rates of K (0–60 kg K ha^?1 as potassium chloride) were applied. Significant grain yield responses to applied N and K occurred for both crop species at all sites of the experiment, and the NxK interaction was significant. Canola required an average of 26% more applied N and 32% more applied K than wheat to produce 90% of the maximum grain yield. Applying increasing rates of K increased the rate of N required for 90% of maximum grain yield. Likewise, applying increasing rates of N increased the rate of K required for 90% of the maximum grain yield. Fertilizer K had no significant affect on the concentration of oil in canola grain or concentration of protein in both canola and wheat grain. Application of increasing rates of N decreased the concentration of oil while increasing the concentration of protein in canola grain, and increased concentration of protein in wheat grain. The NxK interaction was not significant for concentration of oil or protein in grain.     

EXOGENOUS APPLICATION OF POTASSIUM DIHYDROGEN PHOSPHATE CAN ALLEVIATE THE ADVERSE EFFECTS OF SALT STRESS ON SUNFLOWER

A greenhouse experiment was conducted to examine whether foliarly applied potassium + phosphorus (K + P) in the form of monopotassium phosphate (KH₂PO₄) could mitigate the adverse effects of salt stress on sunflower plants. There were two levels of root-applied salt [0 and 150 mM of sodium chloride (NaCl)], and varying levels of KH₂PO₄ [(NS (no spray), WS (spray of water), 5 + 4, 10 + 8, 15 + 12, and 20 + 16 mg g^?1 K + P, pH 6.5] applied foliarly to 18-day old non-stressed and salt stressed sunflower plants. Salt stress adversely affected the growth, yield, photosynthetic capacity, and accumulation of mineral nutrients in the sunflower plants. However, varying levels of foliar applied KH₂PO₄ proved to be effective in improving growth and yield of sunflower under salt stress. The KH₂PO₄ induced growth in sunflower was found to be associated with enhanced photosynthetic capacity, water use efficiency and relative water contents.     

SEED YIELD AND YIELD COMPONENTS RESPONSE OF RAPE (B. NAPUS) VERSUS MUSTARD (B. JUNCEA) TO SULFUR AND POTASSIUM FERTILIZER APPLICATION IN NORTHWEST PAKISTAN

Improper sulfur (S) and potassium (K) fertilizer management, particularly with continued soil nutrient mining, is one of the major factors contributing to low seed yield of canola in northwestern Pakistan. A field experiment was conducted in 2007?2008 on a S and K deficient clay loam soil at the Research Farm of NWFP (Northwest Frontier Province) Agricultural University, Peshawar, Pakistan, with an objective to determine seed yield and yield components response of Brassica oilseed rape versus mustard to S and K application. Twenty treatments in a randomized complete block design were consisted of two oilseed rape (B. napus canola) and mustard (B. juncea canola) genotypes at three rates each of S (15, 30, and 45 kg S ha^?1) and K (30, 60, and 90 kg K ha^?1) fertilizers plus one control (no S and K applied). Seed yield and yield components increased significantly with K and S fertilization as compared to the zero-S/zero-K control. Both genotypes responded positively for seed yield and yield components to K and S fertilization, but the magnitude of response varied with levels of S and K, as well as combined K + S applications. It is concluded that a combination of 60 kg K + 30 kg S ha^?1 would improve seed yield and yield components of rape and mustard in the study area and contribute significantly to increased production. Growing B. napus was better than B. juncea in the study area, because B. napus produced significantly higher seed yield and yield components than B. juncea, indicating that yield components are the most important criteria for selection of Brassica genotypes for higher seed yield.     

Mechanisms of potassium uptake efficiency and dynamics in the rhizosphere of safflower and sunflower in different soils

Potassium uptake efficiency of safflower and sunflower was studied under semi-controlled conditions in loamy and sandy soils. Both species performed better in loamy soil. Safflower had higher agronomic efficiency and higher relative root length under suboptimal K supply. Safflower had higher specific root density and less root radius at all K levels. Safflower had higher relative root-shoot ratio under suboptimal K in loamy soil. Both species had similar K-influx at low and optimal K in loamy soil, while sunflower had higher influx under suboptimal and optimal supplies in sandy soil. Safflower had higher shoot demand in both soils under suboptimal and optimal K. Both species depleted similar amounts of soil solution-K under suboptimal K in sandy soil, while sunflower was more efficient under suboptimal levels in loamy soils. Sunflower depleted more extractable-K under both suboptimal and optimal K. Safflower could be considered K-uptake efficient crop.     

Prospects and challenges in utilization of indigenous rocks and minerals as source of potassium in farming

Potassium (K) is one of the essential nutrients required by crops in large quantities; however, its use in agriculture by farmers is less than required in developing countries. This neglect has led to excess mining of K in soils by crop plants and has resulted in a negative balance of K in soils. This loss necessitates the need of more use of potassium fertilizers in agriculture. Rocks and minerals offer a potential fertilizer to utilize in agriculture as source of K. The crop trials revealed that feldspar, mica, glauconite, nepheline and shoenite are good sources of K for crops, especially in highly weathered acid soils. However, some researchers have reported no agronomic benefit of feldspar or granite rock application to crops. Overall the size modification, acidulation, microbial inoculants and preparation of K-enriched compost are the effective techniques to utilize K-bearing rocks and minerals. Very limited information is available on these aspects. Thus, in this review, an attempt has been to consolidate up-to-date information of indigenous rocks and minerals as possibilities for alternate sources of K for crop plants. Moreover, this area of research needs attention to utilize indigenous K sources, which can aid to limit the import and cost, of the establishment of potash fertilizer-based industries in developing countries.