Critical potassium potentials for crops. I. The effect of soil type on the growth of ryegrass and creeping red fescue

The quantity: potential relationships for Ca→K exchange in six soils were evaluated, where potential is defined by ΔG_K,Ca+Mg. Using the percentage K saturation of the CEC as the index of quantity, the Worcester Series soil, rich in hydrous micas, was shown to have the highest concentration of K selective sites, and Newport Series soil, with mainly kaolinitic clay, the lowest. The other soils, containing mainly smectites, had intermediate K selectivities. An algebraic transformation of this relationship to separate the effects of exchangeable K and CEC showed that 0.01 m C_aCl₂ released more K than m ammonium acetate. From the exchangeable K : ΔG relationship, two regions of K buffering were observed for all but the Newport soil, the transition occurring at a mean ΔG_K,Ca+Mg value of ?20.7 kJ mol^?1, signifying the K concentration below which K from ‘perlpheral’ regions of micaceous minerals is released. This may explain why the percentage K saturation of the CEC of a soil cropped exhaustively (without K manuring) in the field does not drop below a minimum value. Based on pot experiments, exhaustion and optimum K potentials (ΔG_exh and ΔG_opt) were derived from second-degree polynomials fitted to the response curves of plant dry matter yield against ΔG_K,Ca+Mg for five soils, the Worcester soil showing little response. ΔG_exh was inversely related to the 2 : 1 layer silicate content of the soil (r²=0.98 and 0.94 for ryegrass and fescue respectively), and similarly, ΔG_opt, to their CEC values (r²=0.74 and 0.77). Potassium uptake was more closely correlated with exchangeable K than with ΔG_opt.     

Potassium efficiency mechanisms of wheat,barley, and sugar beet grown on a K fixing soil under controlled conditions

Plant species differ in their potassium (K) efficiency, but the mechanisms are not clearly documented and understood. Therefore, K efficiency of spring wheat, spring barley, and sugar beet was studied under controlled conditions on a K fixing sandy clay loam. The effect of four K concentrations in soil solution ranging from low (5 and 20 μM K) to high (2.65 and 10 mM K) on plant growth and K uptake was investigated at 3 harvest dates (14, 21, and 31 days after sowing). The following parameters were determined: shoot dry matter (DM), K concentration in shoot dry matter, root length (RL), root length/shoot weight ratio (RSR), shoot growth rate/average root length ratio (GR_s/aRL), K influx, and soil solution K concentrations. Wheat proved to have a higher agronomic K efficiency than barley and sugar beet, indicated by a greater relative yield under K‐deficient conditions. As compared to both cereals, sugar beet was characterized by higher K concentrations in the shoot dry matter, only 30—50 % of the root length, 15—30 % of the RSR and a 3 to 6 times higher GR_s/aRL. This means that the shoot of sugar beet had a 3 to 6 times higher K demand per unit root length. Even at low K concentrations in the soil solution, sugar beet had a 7 to 10 times higher K influx than the cereals, indicating that sugar beet was more effective in removing low available soil K. Wheat and barley were characterized by slow shoot growth, low internal K requirement, i.e. high K utilization efficiency, and high RSR, resulting in a low K demand per unit root length. At low soil K concentrations, both cereals increased K influx with age, an indication of adaptation to K deficiency. The mechanism of this adaptation merits closer investigation. Model calculations were performed to estimate the K concentration difference between the bulk soil and the root surface (ΔC_L) needed to drive the measured K influx. For the two cereals, the calculated ΔC_L was smaller than the K concentration in the soil solution, but for sugar beet, ΔC_L was up to seven times higher. This indicates that sugar beet was able to mobilize K in the rhizosphere, but the mechanisms responsible for this mobilization remain to be studied.     

Nitrogen requirement of fodder and sugar beet (Beta vulgaris L.) cultivars under high-yielding conditions of northwestern Europe

This study provides current data on plant nitrogen (N) uptake required for maximum sugar yield (PNUp_max) and the corresponding fertilizer N dose (ND) (optimum N dose [ND_opt]) for high-yielding beet crops (sugar yield up to 20 Mg ha^?1). In 2010 and 2011, field experiments were conducted with four cultivars from Beta genus differing in dry matter composition, and six mineral NDs (0–200 kg N ha^?1) at three sites (The Netherlands, Germany, Denmark). Differences between cultivars in PNUp_max and ND_opt were small; however, environments (defined as combination of site and year) substantially differed from each other: highest PNUp_max and lowest ND_opt occurred at environments supplying high amounts of N from soil resources, and vice versa. The level of maximum sugar yield (SY_max) was related neither to PNUp_max (200–270 kg N ha^?1) nor to ND_opt. However, N dose and plant N uptake required for 95% of maximum sugar yield was 50–80 kg N ha^?1 lower than for maximum sugar yield. To conclude, accepting a slight reduction in sugar yield might allow for a substantial decrease in the ND. Cultivar choice and yield level need not to be taken into account at present.     

Cover crop effects on soil structure and early sugar beet growth

Cover crops can improve soil properties, especially soil structure, through organic matter input and rooting activity. However, large variations exist among cover crops, which may lead to differences in the extent of these effects. In this study, cover crops with differing properties were compared regarding soil structure and subsequent sugar beet growth. Field experiments were conducted at two Luvisol sites in Central Germany. Four cover crops (oil radish, saia oat, spring vetch and winter rye) were compared with fallow. Cover crop effects on soil water, N_min content, soil structure and subsequent early sugar beet growth were studied. Additionally, sugar beet received either no or optimal N fertilizer application. Rye and radish had the highest and vetch the lowest above- and belowground biomass. Soil water content was hardly affected by cover cropping, while topsoil N_min contents in April were increased. Penetration resistance was lowered, and aggregate stability was increased by the cover crops, especially oil radish, while values after spring vetch were similar to those of fallow. Differences among the cover crops might be because of a differing root biomass. Independent of N fertilizer application, sugar beet biomass in May tended to be higher after all cover crops, in particular under oil radish. The higher aggregate stability and lower penetration resistance were found to be beneficial for early sugar beet growth. Thus, sugar beet can benefit from a 1-year cultivation of preceding cover crops. Modifications of this effect through cover crop root biomass and architecture as well as repeated cover cropping need to be investigated in further studies.     

Effect of Two Magnesium Fertilizers on Leaf Magnesium Concentration,Yield, and Quality of Potato and Sugar Beet

Twelve field experiments were conducted to study the impacts of calcined magnesite and Kieserite fertilizers on yield, quality and leaf concentrations of magnesium (Mg) in potatoes and sugar beet. The rate of Mg applied was 60 kg Mg ha^?1, and the experiments were realized in six locations for both crop species. There were clear increases in leaf Mg concentration and yield of both crops resulting from application of Mg fertilizers. Mean increase in leaf Mg concentration and crop yield for both species were more pronounced with Kieserite than with calcined magnesite. Sugar concentrations of sugar beet and dry matter yield of potatoes were, however, influenced only slightly by the Mg fertilizers. It seems that superiority of Kieserite to calcined magnesite is related to higher Mg solubility of Kieserite. Use of Mg fertilizers with higher solubility helps to avoid the risk of Mg deficiency and subsequent losses in yield and economic returns.     

Kemink subsoiling before and after planting

The Kemink exact soil management system is a non-inversion soil management system based on subsoiling, ridges and controlled traffic. Previous studies have documented benefits of the Kemink system used in its entirety, but the isolated effect of Kemink subsoiling has not been investigated before. To determine the isolated effect of Kemink subsoiling before and after planting two field experiments in sugar beet and barley were conducted in 1999 and 2000 under low nutrient input conditions in a conventional soil management system without recognized compaction problems. Kemink subsoiling after planting generally showed a negative effect on the growth and yield of both crops, whereas subsoiling before planting increased sugar beet yield from 8.4 to 9.5 t ha⁻¹ and sugar beet nitrogen uptake from 48.5 to 57.4 kg ha⁻¹. There was no effect of subsoiling before planting on the grain yield of barley. The negative effect of subsoiling after planting was more pronounced in 1999 than in 2000, and more pronounced in spring barley. The study shows that Kemink subsoiling after planting involves a significant risk of crop damage and cannot be expected to improve crop performance in conventional soil management systems in its current form, whereas Kemink subsoiling before planting may have potential as a measure to increase yield of sugar beet and possibly other row crops too, under low nutrient input conditions.     

Potassium fertilization on sandy soils in relation to soil test,crop yield and K-leaching

To study the influence of potassium (K) fertilizer rate on soil test K values, crop yield, and K-leaching in sandy soils, four long-term fertilizer experiments (0–60–120–180 kg K ha^?1 a^?1) were initiated in 1988 in northern Germany on farmers fields. Clay content of the plow layer was about 4%, and organic matter between 2% and 5%. Plant available soil K was estimated with the double lactate (DL) method. Small grain cereals (rye and barley) did not respond to K fertilization in the 7-year period even though the soil test value of the K-0 plots decreased from ca. 90 to ca. 30 mg K_DL kg^?1 within 3 years. This value remained almost constant thereafter. Crop removal (including straw) of 75 kg K ha^?1 a^?1 was therefore apparently supplied from nonexchangeable K fractions. Compared to the optimum, no K application reduced the yield of potato by up to 21%, and that of white sugar yield up to 10%. Maximum potato yield was obtained by annually applying 60 kg K ha^?1 which resulted in a test value of 60 mg K_DL kg^?1 soil. Maximum potato yield was also obtained at 40 mg K_DL kg^?1 soil, however, with a single application of 200 kg K ha^?1. Similar results were obtained with sugar beet. This indicates that for maximum yield, even for K demanding crops, it is not necessary to maintain K_DL values above 40 mg K kg^?1 soil throughout the entire crop rotation. Soil test values increased roughly proportional to the K fertilizer level. About 120 kg fertilizer K ha^?1 a^?1, markedly more than crop K removal, was required to maintain the initial K_DL of 90 mg kg^?1. The K concentration of the soil solution in the top soil measured after harvest was increased exponentially by K fertilizer level and so was K leaching from the plow layer into the rooted subsoil. The leached quantity increased from 22 kg K ha_?1 a_?1 in the plot without K application to 42.79 and 133 kg Kha^?1 a^?1 in plots supplied with 60, 120 and 180 kg K ha^?1 a^?1 respectively. Soil test values around 100 mg K_DL kg^?1 on sandy soils, as often found in the plow layer of farmers fields, lead to K leaching below the root zone that may exceed the critical K concentration of 12 mg K T^?1 for drinking water.     

IMPACT OF CONTINUOUS SUGAR BEET CROPPING ON POTASSIUM QUANTITY-INTENSITY PARAMETERS IN CALCAREOUS SOILS

One hundred-eighteen surface soil samples (59 samples from cultivated areas and 59 samples from virgin soils) were studied to ascertain if potassium (K) quantity-intensity (Q/I) parameters of the soils are being changed by long-term sugar beet cropping. Long-term cultivation resulted in a significant decline in the equilibrium activity ratio (AR_e ^K) values from 0.012 to 0.0047 (moles/L)^1/2 (a drop of 61%) and from 0.013 to 0.008 (a drop of 38%) in Typic calcixerpts and Typic endoaquepts, respectively. Paired t-test revealed that continuous sugar beet cultivation led to significant changes in the easily exchangeable K (ΔK₀) values from ?0.69 to ?0.28 cmol_c/kg (a rise of 59%) the Typic calcixerepts soils. The highest values for PBC^K were associated with the soil types which had the greatest clay contents and smectite clay minerals. Results suggest that continuous sugar beet cropping caused a great decline in K supplying power of the soils.     

A SIMPLE AVAILABLE SOIL NITROGEN INDEX

Available soil-N values in commonly cultivated East African soils were determined in the laboratory by several methods, and correlated with one another. Mineralizable-N was correlated more with total-N than with organic-C. The values of mineralizable-N (Δ mineral-N) obtained on aerobic incubation were correlated with crop yield and nitrogen uptake in greenhouse experiments. The yield of dry matter and N uptake by the tomato crop in the absence of applied nitrogen were significantly correlated with Δ mineral-N in the soils; the degree of correlation decreased with increasing rates of fertilizer-N applied and Δ mineral-N and dry-matter yield were not correlated at the largest rate used. N uptake by the crop was significantly correlated with Δ mineral-N at all rates of applied nitrogen. The Δ mineral-N value determined on soil samples conditioned by 6 weeks incubation followed by 3 weeks air drying was considered to provide a good index to available nitrogen.     

Growth and canopy structure of rice plants grown under field conditions as affected by Si application

Abstract

The ontogenetic changes of N, P, and K contents in leaves of rice, maize, soybean, adzuki bean, potato, and sugar beet were studied as the following results were obtained.

1. N content of rice and maize drastically changed at the primordia formation stage, while that of other crops did not show clear changes depending on the stage of growth.

2. P content of rice and maize was higher in upper leaves than lower leaves, but did not change appreciably in other crops.

3. K content of potato and sugar beet remained constant for a long period of time compared to other crops.

4. P-N relationship in rice and maize distinctly differed between upper and lower leaves; ratio of P content to N content of upper leaves was higher than that of lower leaves.

5. K-N relationship in potato and sugar beet was very different from that in other crops; K content remained constant regardless of the decrease in N content except for the lower leaves.

Thus, as the P-N balance of rice and maize (Gramineae crops) and K-N balance of potato and sugar beet (root crops) showed distinctive characteristics compared to other crops, the physiological significance of the mineral balance must be further investigated.     

Beziehungen zwischen Bodenfruchtbarkeitskennziffern,Ertrag und Inhaltsstoffen von Zuckerrüben auf Löß-Schwarzerde

Relations between soil fertility parameters and sugar beet yield and quality characteristics respectively, on Haplic Chernozem soils In interpreting four “experiments without interference” (VoE) on a total of 435 plots the influence of soil fertility parameters (BFK_i) as organic matter, P, K, Mg, pH value, Cu, B and Mn on sugar beet yield and its nutrient contents on Haplic Chernozem sites under Ca immission has been analysed. “VoE” is a method applied to find specific field data by means of which relations within the multidimensional system soil - plant are ascertained by utilizing soil and yield parameter variations. With increasing pH value the nutrient contents in the soil decreased in the order the following sequence: Mn, Mg. Cu, B; and, resulting from that, the sugar beet yield decreased significantly. The coefficients of determination (B) of the triple linear regression between yield and BFK_i ranged from B = 0,21 to B = 0,33 and between nutrient contents and BFK_i from B = 0 to B = 0,41. Most of the regression functions contained “BFK_i boron” as a variable. It has been found that there were positive correlations between “BFK_i pH value” and “soluble ashes” and negative correlations between “BFK_i pH value” and P contents in sugar beet.     

Sugar beet (Beta vulgaris L.) response to diammonium phosphate and potassium sulphate under saline–sodic conditions

Salinity and sodicity are prime threats to land resources resulting in huge economic and associated social consequences in several countries. Nutrient deficiencies reduce crop productivity in salt‐affected regions. Soil fertility has not been sustainably managed in salt‐affected arid regions. Few researchers investigated the crop responses to phosphorus and potassium interactions especially in saline–sodic soils. A research study was carried out to explore the effect of diammonium phosphorus (DAP) and potassium sulphate (K₂SO₄) on sugar beet (Beta vulgaris L.) grown in a saline–sodic field located in Kohat district of Pakistan. The crop was irrigated with ground water with EC_iw value of 2.17–3.0 dS/m. Three levels each of K₂O (0, 75 and 150 kg/ha) as K₂SO₄ and P₂O₅ (0, 60 and 120 kg/ha) as DAP were applied. The application of P significantly affected fresh beet and shoot yield while K fertilizers had significant effect on fresh beet yield and ratio of beet:shoot, while non‐significant effects on the fresh shoot were observed. The application of K₁ and K₂ promoted sugar beet shoot yield by 49.2 and 49.2% at P₁ and 64.4 and 59.7% at P₂, respectively over controls. In comparison with controls, fresh beet yield was increased (%) by 15 and 51, 45 and 84, and 50 and 58 for corresponding K₁ and K₂ at P₀, P₁ and P₂, respectively. Addition of P₁ and P₂ increased beet yield by 37 and 47% over control. The shoot [P] (mmol/kg) were achieved as 55.2, 73.6 and 84.3 at P₀, P₁ and P₂, respectively. The shoot [Mg] and [SO₄] tended to decrease with increasing P levels, while [SO₄] was markedly reduced at P₂. The effect of P on leaf [Na] was non‐significant, but increasing levels of K decreased [Na] substantially at P₀ and P₁, but there was no difference in the effect of K level on [Na] at P₂. Consequently, K application reduced leaf Na:K ratios. Fresh shoot yield was weakly associated with leaf [P] (R² = 0.53). The leaf Na:K ratio showed a negative relationship (R² = 0.90) with leaf [K]. A strongly positive relationship (R² = 0.75) was observed between leaf [K] and fresh beet yield. The addition of K₂SO₄ also enhanced [SO₄] and SO₄:P ratios in leaf tissues. The ratio of Na:K in the shoot decreased with increasing K application. These results demonstrated that interactions of K and P could mitigate the adverse effects of salinity and sodicity in soils. This would contribute to the efficient management of soil fertility system in arid‐climate agriculture.     

作物对盐分的吸收及其盐害的预测预报

通过温室和田间试验,研究小麦和甜菜在盐胁迫下的生长及其对盐分的吸收。结果表明,小麦耐热略低于甜菜,Ｎａ＾＋抑制小麦和甜菜对Ｋ＾＋和Ｃａ＾２＋的吸收,小麦和甜菜的相对干物质重与土壤含盐量的关系符合Ｍａａｓ－Ｈｏｆｆｍａｎ模型,小麦和甜菜叶Ｎａ＾＋含量与土壤含盐量呈显著正相关,且与干物质重的关系也符合Ｍａａｓ－Ｈｏｆｆｍａｎ模型,文中提出了利用作物叶的Ｎａ＾＋含量与相对干物质重之间的Ｍａａｓ－Ｈｏｆｆ     

Reaktion der Zuckerrübe (Beta vulgaris var. altissima) auf die Kaliumdüngung – ein 20‐jähriger Feldversuch

Response of sugar beet ( Beta vulgaris var. altissima ) to potassium fertilization—a 20‐year field experiment A long‐term fertilizer experiment was performed to develop a K fertilization strategy to achieve highest extractable sugar yields (BZE). Sugar beet was grown in a crop rotation with wheat and barley on an alluvial soil (clayic silt) in Lower Saxony with annual recycling of straw and beet tops, respectively. Since 1983, the treatments were as follows: 1) K fertilization with 0, 29, 58, 87,174, and 524 kg K ha^–1 a^–1 corresponding to 0, 0.5, 1, 1.5, 3, and 9 times the average annual K removal by the marketable products of the crop rotation—since 1995, the two highest treatments (3 and 9 times the removal) received only 174 kg ha^–1 every third year; 2) K fertilization according to the average K removal, given each year (58 kg K ha^–1) or every third year (174 kg ha^–1) to sugar beet; 3) annual K fertilization of 87 kg K ha^–1 (1.5 times the removal) applied in autumn or spring, respectively; 4) annual K fertilization, applied as mineral fertilizer or as organic material (recycling of grain and straw or root and leaves); 5) application of 29 kg NaCl ha^–1 to sugar beet supplemental to a yearly application of 58 kg K ha^–1. Both root yield and soil concentration of lactate‐soluble K increased with K fertilization up to the highest K treatment. The extractable sugar content reached a maximum at a yearly application of 174 kg K ha^–1. Averaged over years, the extractable sugar yield (BZE) increased up to the highest K application. The time of K application (autumn or spring) and the source of K (mineral fertilizer or organic material) had no effect on BZE. An additional fertilization with NaCl increased BZE only slightly in single years. Low‐grade muriate of potash containing 33% K and 3% Na can thus be used. The economically optimal K‐fertilization rate was 174 kg K ha^–1 given once in the crop rotation to sugar beet. A soil K concentration of about 110 mg (kg soil)^–1 (lactate‐extractable K) is sufficient in this soil to achieve a high BZE.     

Growth and phosphorus uptake of maize cultivated alone,in mixed culture with other crops or after incorporation of their residues

Intercropping or rotating of P‐efficient crop species which mobilize sparingly soluble P by their root exudates can have beneficial effects on growth and P uptake of P‐inefficient species. We aimed at studying the effect of intercropping or incorporating of crop residues of P‐efficient crops on the components of maize P‐uptake, i.e. the root‐system size and P influx (P‐uptake rate per unit root length). This was studied in 3 pot experiments in a low‐P sandy soil. In the first experiment, maize was intercropped with white lupine, sugar beet or oilseed rape, and with groundnut in the second experiment. In the third experiment, maize was grown after incorporating the crop residues of white lupine, sugar beet or oilseed rape. Maize growth and yield was strongly inhibited when intercropped with white lupine, sugar beet or oilseed rape, probably because of competition for nutrients. But with groundnut as the accompanying species, maize yield was increased by a factor of 3, mainly because of an enhanced P influx. Crop residues of oilseed rape and sugar beet increased the yield of maize by factors 2 and 1.6, respectively, because of a 3 and 2 times higher P uptake as compared to maize grown after maize without incorporation of crop residue. The reason for the higher maize P‐uptake after oilseed rape was an 11 times higher P influx as compared to maize without crop residues, and after sugar beet residues because of an enhanced root growth and a 4 times higher P influx. Lupine residues did not improve maize growth, mainly because of a low P influx, which was even less than that of maize grown without crop residues. The soil solution P concentration and calcium acetate lactate‐extractable P (CAL P) measured in this study did not reflect the P availability as indicated by the plants (P uptake, P influx). This indicates that other mechanisms such as P mobilization in the rhizosphere by root exudates or cell‐wall components were responsible for the increased P availability. These mechanisms need further investigation.     

Beziehung zwischen dem durch K-Düngung erzielbaren Mehrertrag und dem K-Gehalt der Böden nach Feldversuchen in der Bundesrepublik Deutschland

Relationship between the maximum yield increase from K fertilization and the K content of the soils after field trials in the Federal Republic of Germany Several hundred long term potassium field experiments with crop rotation and with plant residues like straw and sugar beet leaves removed from the fields, on different soils of the FRG were evaluated. The K content in the top soil was determined by the DL and CAL methods (K(lact)), given in mg K₂O/100g soil. No relationship could be found between K(lact) and the maximum possible yield increase for wheat, barley, sugar beets, and potatoes, if K(1act) was >5 mg/100g. It seems unnecessary, therefore, raise the K content of the soils. Occasional significant positive yield response should be less emphazised than average yields. Economical average yield increases on K fertilization were found with sugar beets and potatoes, rarely with barley but never with wheat. In all longterm trials the K amount of fertilizer required for maximum possible yield increase was above the amount of K removed by the crop. 7 to 27year field trials on clayer soils show that the K content of the soil may drop to 5-10mg K20(CAL) without causing increased yield response to K fertilization. The yield responses to K fertilizer are dependent to a high degree on the season (weather conditions), as was shown by high yield increases in exceptionally dry seasons. The large content of plant available Kin the top soils was due to high K fertilization during the past decades and the illitic nature of the soils. From the results of the field trials it may be concluded that an amount of K fertilizer which replaces K removed by the crop is sufficient for all soils with 5-10mg K₂O; for > lOmg K₂O(lact) K fertilization can be less than actual K removal. Because of large variations, the K(lact) figures (chapter 5),are of very limited value for predicting fertilizer requirements. The average K fertilizer consumption used (1981/82) of the FRG was higher than the K removed from soils by 79 kg K₂O/ha (in 1982). Official recommendations of K fertilizer in the FRG as well as the amounts of K actually applied are both in disagreement with the results of fertilizer experiments in the field.     

轮作下华北寒旱区作物生产的氮磷养分效果分析

明晰华北寒旱区主栽作物的氮、磷养分利用效果,能够发挥作物生态适生性与养分高效性优势,是作物充分利用区域自然-社会资源进行生产配置技术创新的理论依据。在河北省张北县砂质栗钙土农田,采用交叉式种植方法,设计了包括马铃薯、亚麻、谷子、莜麦、甜菜等5种作物的轮作试验,研究在轮作条件下华北寒旱区主栽作物的养分利用效果。结果表明, 5种作物间生物产量相差1.17～2.34倍,甜菜最高(10 291 kg·hm~(-2)),莜麦次之,亚麻最低(4 393kg·hm~(-2)),作物间产量差异性显著;5种作物氮、磷携出量分别相差1.03～2.10倍、1.00～1.92倍,甜菜氮素携出量最高(199 kg·hm~(-2)),莜麦磷素携出量最高(29 kg·hm~(-2)),亚麻氮、磷携出量均最低(分别为95 kg·hm~(-2)、15 kg·hm~(-2));氮、磷养分生物学效率分别在43.82～53.11 kg·kg~(-1)、287.60～574.88 kg·kg~(-1),其中甜菜氮、磷养分生物学效率最高; 5种作物氮、磷产投比变化在0.50～1.65、0.34～1.83,莜麦氮、磷产投比最高。在华北寒旱区,作物种类是引起作物产量、氮磷携出量及氮磷养分生物学效率差异的主要因素,茬口对诸性状的影响不明显。甜菜是对氮、磷吸收高效利用的高产作物,莜麦是对农田供给氮、磷高效利用的作物;马铃薯作为甜菜的前茬、甜菜作为莜麦的前茬更有利于提高作物产量。     

Yield of sugar beet,soybean, corn,field bean,and wheat as affected by lime application on alkaline soils

Abstract

Environmental regulations and limited storage space compel processors to remove spent limestone and not stockpile it on site. This material is often used as a liming material to control pH on acid soils, but in some cases may have to be applied to alkaline soils. This study was undertaken to evaluate the effect of applying sugar beet processing lime on soils with an alkaline solum. Studies were conducted at seven sites representing four soil series. Lime was applied at rates of 0,1.4, 2.8, and 5.6 magnesium (Mg) ha^‐1. Sugar beet (Beta vulgaris L.), soybean (Glycine max L.), cora (Zea mays L.), field bean (Phaseolus vulgaris L.), and wheat (Triticum aestivum L.) were used as test crops. Yield of sucrose and roots of sugar beet as well as yield of soybean, corn, field bean, and wheat were not affected by lime application. Manganese (Mn) and zinc (Zn) concentration in leaves of sugar beet and soybean, and whole field bean plants decreased with increasing lime rates. These results show this lime may be applied at rates up to 5 Mg ha^‐1 once every three years on these alkaline soils without negatively affecting the yield of sugar beet, soybean, corn, field bean, and wheat. Nutritional status of these crops should be carefully monitored after lime application.     

The effects of potassium fertilization on water‐use efficiency in crop plants

The supplies of water and nitrogen to a plant during its critical stages of growth are the main factors that define crop yield. A crop experiences irregular water deficits during its life cycle in rain‐fed agriculture. An effective anti‐stress‐oriented approach therefore ought to focus on increasing the units of water productivity. The main objective of this conceptual review is to confirm that adequate K management can be used as an important tool to alleviate the negative effects of water deficit on plant growth, yield‐component formation, and yield. The French and Schultz approach of using the water‐limited yield (WLY) was modified in this review into a graphical form and was used to discriminate between yield fractions that depended on the volume of transpired water from those that were induced by K fertilizer. By using this method, it was possible to demonstrate the extent of several crop (winter wheat, spring triticale, maize, sugar beet) responses to the K supply. Yield increases resulting from K application mostly appeared under conditions of mild water deficit. As described for sugar beet, finding the critical period of crop K sensitivity is a decisive step in understanding its impact on water‐use efficiency. It has been shown that an insufficient supply of K during crucial stages in the yield formation of cereals (wheat, spring triticale), maize, and sugar beet coincides with a depressed development in the yield components. The application of K fertilizer to plants is a simple agronomic practice used to increase crop tolerance to a temporary water shortage. It may be that the improvement of a plant's access to K during mild water‐deficiency stress will increase water uptake by the root cells, which in turn increases their osmotic potential and thereby allows extension growth. This growth in turn promotes access to other mineral elements (including nitrogen) and water, which favor plant growth and yield.     

Wirkung differenzierter K-Düngung auf bodenphysikalische Eigenschaften,Bodenwassergehalt und Ertrag von Zuckerrüben und Sommergerste auf einem Tschernosem im Mitteldeutschen Trockengebiet

The water balance in the soil profile and soil moisture dynamic (available water content [%]) under sugar beet 2009 and spring barley 2010 were investigated in selected treatments of a long-term K-fertilization trial on a chernozem developed from loess in Bernburg, Germany (21% clay, 73% silt, 1.5% C_org), which received an annual K-fertilization of 0/0 and 249/124.5 kg ha^?1, respectively, to sugar beet/spring barley within the last 14 years. Intensive K-fertilization increased the K content of topsoil and subsoil as well as available water capacity up to 60 cm soil depth. Under water stress conditions in August 2009, the treatment with high K-fertilization achieved the highest sugar beet yield, sugar content (°S) and white-sugar-yield at final harvest. Combined with the higher beet yield, the water use efficiency was also increased and the water pool of the subsoil was used more efficiently. In the following year (2010), weather conditions were relatively wet. Under these conditions, no differences in yield parameters and water consumption of sugar beet and spring barley between both K-levels were observed.