重庆酸性紫色土马铃薯的高产优质与养分平衡

Over a period of two years,field experiments were conducted on four silty loam soils grown with foliar vegetable crops inculding Chinese cabbage(Brassica pekingensis Rupr.,cv.Lu-Bai 3),autumn greens (B.chinensis L.,cv.Piao-Geng-Bai),winter greens(B.var.rosularis Tsen et Lee,cv,You-Dong-Er),and summer greens(B.chinensis L.,cv.Zao-Shu5),respectively,Each eperimpent included one CK treatment without K,N and Pfertilizers applied,and four treatments with from low to high doses,0-300 kg hm^-2 for Chinese cabbage,0-150 kg hm^-2 for autumm and winter greens and 0-180 kg hm^-2 for summer greens,of K fertilizers in the form of sulfate of potash(SOP)applied together with N and P fertlizers,One treatment of K fertilizer in the form of muriate of potash(MOP) applied at high levels(150 or 180 g hm^-2)together with N and P fertilizers was included in the experiments of autumn,winter and summer greens ,respectively,in order to compare the effcts of SOP and MOP ,The market yields of the tested crops incresaed significantly with the increasing rate of K application.The crops supplied with K fertilizers yielded more stably as the CV% of their yields decreased with the rate of K application.K fertilization increased not only K contents but also the amounts of N ,P and K absorbed in shoots of autumn,winter and summer greens,which were atatistically significantly correalted to their yields.In can aslo be found that potassium improved the quality of the foliar vegetable crops as their dry mater contents were generally increased and Vc contents obviously increased and nitrate contents markedly decreased ,As compared to MOP,SOP was more effective on the yields and quality of autumn,winter and summer greens at the high levels of fertilization.     

Combined N,P, K fertilization and liming maximises crop productivity of acid loams in Lithuania

Crop response to fertilization and liming was investigated in field and pot trials on sandy loam Dystric Albeluvisols (pH 4.2–4.3). Treatments in the field trial were: 1, no fertilizer; 2, PK; 3, NK; 4, NP; 5, NPK; 6, lime; 7, lime+PK; 8, lime+NK; 9, lime+NP; 10, lime+NPK. In the pot trial, they were: 1, no fertilizer; 2, N; 3, P; 4, K; 5, NP; 6, NK; 7, PK; and 8, NPK applied to unlimed and limed soils. All treatments were in four replicates. Crops sensitive to soil acidity (winter wheat, fodder beet, spring barley and clover-timothy ley) and the less acid-sensitive winter rye, potatoes, oats and lupins and oats mixture were sown in the field trial. In the pot trial, the acid-sensitive spring barley and red clover, and the less acid-sensitive oats and lupin-oats served as the test crops. Combined application of fertilizers (NPK) increased yields of crops sensitive to soil acidity in plots receiving lime by 23%, and those of crops less sensitive to soil acidity by 18% in comparison to crops grown on unlimed soils. The results of pot experiments corroborated the field results. When N was applied alone, crop yields were always higher than those recorded for P or K treatments on both the unlimed and limed treatments. N application proved to be a prerequisite for high crop yields in the soils investigated. Thus, the efficiency of P and K fertilizers increased in the order NK<NP<NPK, with the effects being accentuated more in the limed than in the unlimed treatments. The results demonstrated the importance of multi-nutrient (NPK) fertilization in combination with liming for enhancement of high crop productivity in the unlimed soil investigated. N applied alone in combination with liming produced relatively good yields; hence, where resources are limited for the purchase of P and K fertilizers, applying N and lime can be a viable option in the short term.     

Potential mineralization and nitrification in volcanic grassland soils in Chile

Abstract

A proportion of the nitrogen (N) applied to grasslands as organic or inorganic fertilizers can be lost to water courses as nitrate and to the atmosphere as nitrous and nitric oxides. Volcanic soils from Chile are not generally prone to leaching, possibly due to net immobilization of nitrate and/or ammonium, and/or due to inhibition of nitrification by either chemical or physical processes. In laboratory studies we found large mineralization potentials in soils from three different Chilean soils after 17 weeks of incubation, totalling 215 and 254 mg kg^?1 dry soil for two Andisols and 127 mg kg^?1 dry soil in an Ultisol. Nitrification occurred after a short period, and was lowest in the Ultisol. In addition, microbial analysis showed nitrifiers to be present in all three soils. Adsorption of ammonium was two-fold stronger than for nitrate, ranging from 29 to 180 kg N ha^?1. The highest potential for N adsorption in the 0–60 cm soil profile was with the Ultisol (398 kg N ha^?1), but was similar in both Andisols (193 and 172 kg N ha^?1, respectively). The combination of ammonium retention together with delayed nitrification could account for the low leaching rates in these soils.     

Erodibility and runoff-infiltration characteristics of volcanic ash soils along an altitudinal climosequence in the Ecuadorian Andes

Soil erosion is a widespread phenomenon in Andean South America, where many regions are covered with soils derived from volcanic parent materials. Climate-induced differences in the genesis of these soils have been demonstrated along toposequences on volcanic slopes. This research was conducted to study the impact of such differential pedogenesis on erodibility and runoff-infiltration characteristics along an altitudinal Entisols–Inceptisols–Andisols sequence in the Andes of northern Ecuador. Surface soils were packed into small pans and placed on a 9% slope, and a simulated rainstorm with varying intensities was applied for a duration of 30 min. The runoff-erosion behaviour of the studied volcanic ash soils is strongly affected by their pedological development. Accumulation of organic matter and precipitation of active amorphous materials at high elevations have led to the formation of well-developed Andisols with very stable aggregate structure. These soils remain wettable when air-dried, show very high infiltration capacity and, consequently, low potential for runoff generation and soil erosion. Low organic matter contents and absence of active amorphous materials at low elevations have led to the formation of weakly aggregated Entisols and Inceptisols. These soils are susceptible to surface crusting, which lowers their infiltration capacity and increases their erodibility. However, in comparison with other soils of different origin and composition, the interrill erodibilities determined for these more erodible low-elevation soils are classified as low. The findings of this study suggest that upland soil erosion is not a major threat to sustainability in the studied volcanic landscape, which is generally confirmed by field observations.     

Crop uptake of cadmium from phosphorus fertilizers: I. Yield and cadmium content

We investigated the effects of different P fertilizers on the yields and Cd contents of oat (Avena sativa L.), ryegrass (Lolium multiflorum L.), carrot (Daucus carota L.), and spinach (Spinacia oleracea L.). These crops were grown in the greenhouse using soils treated with lime to achieve three pHs ranging from 4.77 to 5.94 for a sandy soil and 4.97 to 6.80 for a loam soil. The crop yields were generally not affected by liming or application of different kinds of P fertilizers, with a few exceptions. Application of Cd-containing NPK fertilizers in all cases tended to increase the Cd concentrations in crops, and the highest Cd concentrations in crops were obtained when the high-Cd NPK fertilizer was applied (adding 12.5 μg Cd kg^?1 soil). Cadmium concentrations in crops in most cases decreased with increasing soil pH. The highest percent recovery of the added Cd by plant species in the sandy soil was found for inorganic Cd-salt and in the loam soil for low-Cd NPK fertilizer. Phosphate rock resulted in the lowest recovery of the added Cd by all the plant species in both soils, but was also an insufficient P-source of its low solubility.     

The influence of parent material on soil fertility degradation in the coastal plain of Tanzania

Differences in the vulnerability of soils to fertility degradation are compared for two major soil groups located in the coastal plain of Tanzania and cropped with sisal (Agave sisalana). Ferralsols derived from intermediate gneiss of Precambrian age and Cambisols developed in Jurassic and Neogene limestones partly covered with Quaternary deposits were selected for comparison. A clear influence of parent material was apparent when soils were continuously cropped with sisal and no fertilizers were applied. Serious soil fertility decline occurs in Ferralsols, but Cambisols are resilient to chemical degradation and the fertility decline in these soils was very limited. The differences in degradation rates are explained by the lower initial fertility and low nutrient reserve of Ferralsols, while the Cambisols had higher initial fertility levels and nutrients removed by the sisal crop are replenished by the weathering of the underlying parent material. Sustainable soil fertility management of Cambisols includes only NPK fertilization, but heavy dressings of lime, organic manures and/or chemical fertilizers are required to improve the fertility status of the Ferralsols and to produce crops in a sustainable manner.     

低磷条件下植物根系形态反应及其调控机制

磷是植物必需营养元素之一,土壤中磷有效性低,限制作物生长发育。磷肥施用量逐年增加,但是磷矿资源面临耗竭。植物根系形态变化对于植物适应低磷胁迫,提高植物对土壤磷的吸收利用具有重要意义。本文从植物根系构型、根冠比、初生根、根毛、侧根等方面综述了植物适应低磷胁迫的根系形态变化特征。低磷条件下,植物根系构型发生改变,普遍抑制主根生长,刺激侧根发育起始与伸长,诱导根毛形成。同时,分析了转录因子、植物激素、蔗糖以及关键基因等对低磷条件下植物根系生长发育的生理与分子调控机制,低磷胁迫下转录因子ZAT6和MYB62参与调控初生根生长,BHLH32和PHR调控根毛形成发育,WRKY75对侧根发育有抑制作用。研究表明,在低磷条件下,赤霉素、细胞分裂素、生长素和乙烯对初生根发育起着调控作用,而根毛的生长发育与赤霉素、生长素和乙烯有关,侧根发育过程中生长素作用明显。一些基因如LPR1、LPR2、LPR3以及PDR2参与调控低磷胁迫下植物初生根的发育。低磷胁迫下光合产物蔗糖对植物根毛和侧根发育有影响。     

固、液态磷源在石灰性土壤中的移动性及其对土壤有效磷含量影响的研究

采用同心圆扩散法对固体和酸性液体磷肥在石灰性土壤中的移动性与有效性进行研究。结果表明,土壤Olsen-P含量随施肥点圈层由内向外层而递减,液肥处理的Olsen-P量在施肥点以外的3个土壤圈层中均高于固肥处理。固体肥料大部分停留在距施肥点0~7.5 mm圈层,占施磷总量的55%~70%;液体肥料虽在0~7.5 mm层的含量低于固体肥料(约占15%~40%),但在远离施肥点的后3个圈层(7.5~43 mm)中均高于固体肥料处理,其中7.5~13.5 mm最为明显(液肥占35%,固肥占20%)。3种施磷量在砂土、壤土及粘土上均表现出一致的变化规律。肥料对土壤pH值的影响仅限制在距施肥点最近的0~7.5 mm范围,该层的pH值显著低于后层。本研究说明在石灰性土壤中液体磷的移动性、有效性明显高于固体磷,但对土壤pH值无显著影响。     

施用钾肥对叶菜产量和品质的影响

Over a period of two years, field experiments were conducted on four silty loam soils grown with foliar vegetable crops including Chinese cabbage (Brassica pekinensis Rupr., cv.Lu-Bai 3), autumn greens (B. chinensis L., cv.Piao-Geng-Bai), winter greens (B. var.rosularis Tsen et Lee, cv.You-Dong-Er), and summer greens (B. chinensis L., cv.Zao-Shu 5), respectively. Each experiment included one CK treatment without K, N and P fertilizers applied, and four treatments with from low to high doses, 0~300 kg hm^-2 for Chinese cabbage, 0~150 kg hm^-2 for autumn and winter greens and 0~180 kg hm^-2 for summer greens, of K fertilizers in the form of sulfate of potash (SOP) applied together with N and P fertilizers. One treatment of K fertilizer in the form of muriate of potash (MOP) applied at high levels (150 or 180 kg hm^-2) together with N and P fertilizers was included in the experiments of autumn, winter and summer greens, respectively, in order to compare the effects of SOP and MOP. The market yields of the tested crops increased significantly with the increasing rate of K application. The crops supplied with K fertilizers yielded more stably as the CV% of their yields decreased with the rate of K application. K fertilization increased not only K contents but also the amounts of N, P and K absorbed in shoots of autumn, winter and summer greens, which were statistically significantly correlated to their yields. It can also be found that potassium improved the quality of the foliar vegetable crops as their dry mater contents were generally increased and Vc contents obviously increased and nitrate contents markedly decreased. As compared to MOP, SOP was more effective on the yields and quality of autumn, winter and summer greens at the high levels of fertilization.     

施钾对有些茄科作物产量和品质的影响

Over a period of two years,field experiments were conducted on wto silty loam soils grown with four solanaceous vegetable crops of geggplant(var.serpentinum Bailey),tomato(var.commune Bailey),sweet pepper(var.grossum Bailey) and chilli (var.lengum Bailey),respectively,Each experiment included four treatments with from low to high doses,0-450 kg ha^-1 for eggplant ,tomato and sweet pepper,and 0-270 kg ha^-1 for chilli,of K fertilizers in the from of sulfate of potash(SOP) applied together with N and P fertilizers. One CK treatment without K,N and P fertilzers applied and one treatment of K fertilizer in the form of muriate of potash(MOP) applied at the high level(450kg ha^-1) together with N and P fertilizers were included in the experiments of eggplant,in order to compare the effects of SOP and MOP,The fruit yields of the tested crops increased significantly with the increasing rate of K application.The crops supplied with K fertilizers yielded more stably as the CV% of their yields decreased with the rate of K application,The K fertilizers yielded more stably as the CV% of their yields decreased with the rate of K application,The dry matter and vitamin C contents in fruits of tomato,sweet pepper and chilli,and the sugar content and the titratable acidity level of tomato fruits were increased,and the S/A ratio( ratio of sugar content to titratable acidity) of tomato fruits were decreased by K fertilization,indicating that K fertilization could improve the fruit quality of the solanaceous vegetable crops.However,the high rate of Kfertilizer might lower the dry matter and vitamin C contents of tomato fruits and sewwt pepper fruits.SOP was more effective than MOP in increasing the yield and quality of eggplant fruits at the high fertilization rate;therefore,the choice of applying SOP may be better for high levels of K fertilization.     

Effectiveness of Egyptian phosphate rock on clover production in Ethiopia

Abstract

The majority of soils in Africa are phosphorus (P) deficient, but the high cost of water‐soluble P fertilizers limits their use by resource‐poor farmers. A low‐cost alternative is to use phosphate rocks. We evaluated the effectiveness of Egyptian phosphate rock (EPR) relative to triple superphosphate (TSP) applied at 0, 15, 30, 45, and 60 kg P ha^‐1 to annual Trifolium species grown on a P‐deficient Vertisol. The fertilizers were applied once and their effects were followed on seven consecutive annual clover crops. Clover responded to P at all the rates used. Significant (P<0.05) P effects on clover P content and DM yields were observed up to the fourth crop. Over all the seven crops, EPR was 89% as effective as TSP in increasing herbage DM and 93% as effective in increasing herbage P content. Its substitution rates were 79% for DM yield and 86% for clover P content. Therefore, EPR was highly reactive and its use could elevate the P status of the P‐deficient Vertisols and increase feed and livestock productivity in the Ethiopian highlands.     

我国主产区紫花苜蓿营养状况分析

为探究我国主产区紫花苜蓿营养现状以及生产中肥料使用的科学性, 2012年5-6月,对我国紫花苜蓿主产区21个大田样地苜蓿初花期时的土壤养分、 植物组织营养以及第一茬产草量和施肥管理情况进行测定和调研,对土壤和植物营养状况进行评价,对土壤和植物养分含量与产草量间的关系进行了分析。研究表明, 紫花苜蓿主产区土壤以砂性为主,有机质含量低。紫花苜蓿组织中氮素营养处于充足水平,磷素（P）和钾素（K）普遍缺乏, 微量元素中锌（Zn）、 硼（B）、 钼（Mo）元素缺乏。土壤中磷素和植物体内硼（B）、 钼（Mo）和铁（Fe）含量与第一茬产草量显著正相关。施用氮肥地块有12个,磷肥有5个, 钾肥有3个,没有有针对性施用微量元素肥料的地块。建议在紫花苜蓿大田生产上控制氮肥施用,注重P、 K肥的施用,有针对性地施用B、 Mo等微量元素。     

Free and intra‐aggregate organic matter as indicators of soil quality change in volcanic soils under contrasting crop rotations

Soil physical fractionation techniques may provide indicators of changing soil organic carbon (SOC) content; however, they have not been widely tested on volcanic soils (Andisols). In this study, we assessed two fractions as potential indicators in volcanic soils, using two sites in Chile converted from natural grassland to arable and mixed crop rotations, 8 and 16 yr previously. In the 8‐yr experiment, SOC had declined under all rotations, with smaller changes where the rotation included 3 or 5 yr of perennial pasture. Whereas the average SOC was only 76% of the level in the preceding natural grassland, the corresponding value after 16 yr for the second site was 98% (and 93% under continuous arable), probably reflecting its high allophane clay content. The fractionation procedure tested proved applicable to both Andisols, but the intra‐aggregate light fraction (IA‐SOM, isolated in sodium iodide solution at 1.80 g/cm³ after ultrasonic dispersion) accounted for a very small proportion of total SOC (<1%). We suggest that in Andisols, the free light fraction (FR‐SOM, isolated in sodium iodide at solution of the same density, but prior to ultrasonic dispersion) is stabilised to a greater extent than in nonvolcanic soils, and the intra‐aggregate fraction plays a more minor role as a pool of intermediate turnover. The relative value of each fraction needs to be confirmed through dynamic experiments, using more sites, and including situations where SOC content is initially low.     

Influence of crop rotation, intermediate crops, and organic fertilizers on the soil enzymatic activity and humus content in organic farming systems

The influence of crop rotation systems with different portions of nitrogen-fixing crops, intermediate crops, and organic fertilizers on the enzymatic activity and humus content of soils in organic farming was studied. The highest activity of the urease and invertase enzymes was determined in the soil under the crop rotation with 43% nitrogen-fixing crops and with perennial grasses applied twice per rotation. The application of manure and the growing of intermediate crops for green fertilizers did not provide any significant increase in the content of humus. The activity of urease slightly correlated with the humus content (r = 0.30 at the significance level of 0.05 and r = 0.39 at the significance level of 0.01).     

Phosphorus balances for arable soils in Southern England 1986–1999

The behaviour of P in a range of English arable soils was examined by plotting the change in resin P in the topsoil (ΔPres) at the end of a 3‐ to 5‐year period, against the P balance over the same period (fertilizer P applied minus offtake in crops, estimated from farmers’ reported yields and straw removal). Based on the assumption that values for offtake per tonne of crop yield used for UK arable crops are valid averages, 20–60% of ΔPres was explained by the balance. Applying excess P fertilizer increased Pres, and reducing P fertilizer use decreased it; typically 3–4 kg P ha^?1 was required for each mg L^?1ΔPres (6–8 kg ha^?1 for each mg L^?1 of Olsen P). About half the P balance seems to be resin extractable and this differed little between soil groups, except in cases of very low P (index 0) in which the P buffering was stronger, and on very high P soils (index 4/5) when buffering was less. However, on calcareous soils and red soils, when fertilizer was applied in accord with offtake, Pres fell by up to 4 mg L^?1 year^?1 (2 mg L^?1 yr^?1 olsen P) and to prevent this an extra 3–10 kg P ha^?1 year^?1 fertilizer was required. But on most non‐calcareous soils, replacing offtake maintained Pres, with perhaps slight rises on soils of low clay content or greater organic matter content. In soils under arable rotations, the apparent recovery of P from fertilizer was often around 100%, falling to 85% on Chalk soils and 75% on medium–heavy soils on limestone or Lower Chalk. The fate of the ‘missing’ P needs clarification. The case for corrections to current P fertilizer recommendations in the UK on certain soil types is discussed.     

Potassium sources,microorganisms and plant nutrition: Challenges and future research directions

Until recently, potassium(K) has not received considerable attention because of the general belief that soils contain ample amounts of this element. In addition, low rates of K fertilizer application in agriculture have led to rapid depletion of K in the rhizosphere soil in many underdeveloped countries. This results in various negative impacts, including preventing optimum utilization of applied nitrogen and phosphorus fertilizers. To compensate for these losses,massive use of K fertilizers in ...     

Agrogeochemical cycles of plant nutrients in the territory of Russia

The contribution of mineral fertilization to the agrogeochemical cycles of major nutrients (N, P, K) was estimated. The agrogeochemical budgets of major nutrients (NPK) in the territory of Russia are unfavorable for agricultural production for the present and the nearest future. The removal of major nutrients with crops significantly exceeds their input to the soil with fertilizers and other sources. The nutritional degradation of arable soils increases, which can result in irreversible catastrophic consequences within 20–30 years.     

Phosphorus in agroecosystems on gray forest soils in the opolie regions of Central Russia

Long-term stationary field experiments revealed a poor supply of gray forest soils with available phosphorus, which provides no more than half the amount necessary for optimum nutrition of plants. It was found that agricultural crops with different capacities to assimilate phosphates from the soil and fertilizers have strong requirements for phosphorus fertilizers and abruptly increase their utilization in the production process with increasing level of nitrogen nutrition. Crops with the optimum level of nitrogen nutrition uptake a double amount of phosphorus compared to crops depleted in nitrogen. Clover and barley have an increased capacity to mobilize soil phosphates from the lower horizons at an extremely low content of available forms of them in the plow layer. Winter wheat and corn are characterized by an active uptake of phosphorus applied with fertilizer and its efficient utilization in the production process if the nitrogen supply is not a limiting factor. The level of phosphorus nutrition of subsequent rotation crops increases due to the enrichment of the root-inhabited soil layer with phosphorus from clover root and harvest residues. Based on the data about the unacceptably abrupt decrease in the application of mineral fertilizers in Russian agriculture (90% of fertilizers are exported now), it is shown that the export of fertilizers should be limited at the state level, because chemicals, and primarily phosphorus fertilizers, should be considered strategic resources for internal use only.     

Phosphorus Uptake and Translocation in Field-Grown Maize after Application of Rare Earth-Containing Fertilizer

ABSTRACT

In recent decades, rare earths and rare-earth containing fertilizers along with nitrogen (N) and phosphorus (P) fertilizers have been used by agriculturists to improve crop yield and quality. The interaction between rare earths and N has been explained in soils, yet little is known of the effect of rare earths on P nutrition of field-grown crops. When maize plants entered the early stem-elongation stage, a rare earth-containing fertilizer (lanthanum (La) and cerium (Ce) as major rare earths) was applied to the soil with irrigation water. Ten days after application of rare earths, there was no significant dose-dependent accumulation of P in the roots and shoots, with one exception where P concentrations increased in the roots at a dosage of 100 kg rare earths ha^{? 1}. However, at maturity, the application of rare earths at less than 10 kg ha^{? 1} significantly improved P uptake by field-grown maize and P transport to the grain. The application of rare earths at less than 10 kg ha^{? 1} increased crop yield. Other studies have shown that at rates less than 10 kg rare earths ha^{? 1}, there was no accumulation of heavy metals and rare earths in the grain, and that the present mean application rate of rare earths (< 0.23 kg ha^{? 1} year^{? 1}) currently applied in China was unlikely to affect the safety of grains in arable soils. Together, these field studies can give a scientific understanding of benefits and risks when utilizing rare earths in agriculture, and of the interaction between rare earths and P nutrition in field-grown crops.     

Kinetics of speciation of copper,lead, and zinc loaded to soils that differ in cation exchanger composition at low moisture content

Abstract

A better understanding of the fates of heavy metals in wide range of soils is important in improving efficiency of remediation technologies of heavy metals polluted soils. To contribute to this field we studied the kinetics of speciation of copper (Cu), leaf (Pb), and zinc (Zn) in six soils differed in major cation exchanger composition. Soluble salts of Cu, Pb, and Zn were loaded to the soils, incubated at field moisture contents, and the change in chemical forms of the metals was traced by sequential extraction. In Inceptisols predominated by 2:1 layer silicates and poorly crystalline iron oxides, the added Cu and Pb were found mostly in exchangeable and oxide bound fractions, with decreasing and increasing proportion of the former and the latter during 50 days after addition, respectively. In allophanic and humic Andisols, about 50 to 70% of the total Cu and Pb was found in oxide bound fraction with a significant amount in organically complexed fraction in the latter. The amounts of Cu and Pb in each fraction varied only slightly with time in these soils. The proportion of oxide bound Cu arid Pb was relatively low in a kaolinitic Ultisol irrespective of its higher iron oxide content. Zinc was found mostly in exchangeable and soluble fractions except in Andisols. Low crystallinity of oxide minerals as well as their amount is important factors determining heavy metal retaining capacity of soils. The exchangeable and oxide bound heavy metals should be treated separately in models simulating removal of heavy metal cations by washing and electrokinetic methods.