Abstract:This paper deals with the effects of the rates of potassium fertiliser application rates and the potassium status of three typical tobacco planting soils on the K contents of flue-cured tobacco organs,K distribution,and secondary and trace element contents of cured leaves.The results indicated that K content in cured leaves increased with the potassium rate,which could be fitted by equations.When tobacco was supplied with sufficient potassium fertilizer,the order of K content on plant organs was bud>leaf>stem>root,and on different leaf positions was lower>middle> upper; but in K dificient condition the leaf K content in upper position was higher than that in middle and lower.The percentages of K distribution in tobacco organs were in the sequence Leaf>stem>root>bud.When K content in middle leaf was upper to 2.4% or more,the distribution tended to be balanced and the percentage tended to a constant,being 60%,20%,15% and 5% in leaf,stem,root,and bud,respectively.So,2.4% of K content in middle leaf could be taken as the Critical Value for Balanced Distribution of Potassium under the experimental conditions.The Critical Value gives a new idea to improveing the potassium nutrition of tobacco.
Liu Youcbang , Zhang Lanting , Zhao Jiyu , Wang Yang
Abstract:This paper deals mainly with the mangement of water resources with the chara cteristics of supplemental irrigation for water-saving and prevention of drought,waterlogging and salinization.The indexes for dynamic control of groundwater tables in different seasons are also proposed.The relations between rainfall and the rising of groundwater table,between river-canal irrigation and the rising of groundwater table between evaporation and the decline of groundwater table and between well irrigation and the decline of groundwater table are analysed.Some empirical formulas are obtained from statistical analyses.Finally,according to the principle of both meeting the requirements of irrigation and controlling drought,waterlogging and salinization comprehensively,the management and control sche mes of water resources for different hydrological years in different regions and under the condition of conjunctive use of surface water and ground water are given.
Xiao Zhenhua , B. Prendergast , C. L. Noble
Abstract:Effects of irrigation water quality on salt-water dynamics of red-brown earth and perennial pasture production were studied.Irrigation water with salinities of 100,1500 and 3000mg/L and six different irrigation treatments were adopted in the experiment.Salt was accumulated in the soil during the season of irrigation with water of high soluble salt concentration and partly leached away during irrigation with water of low soluble salt concentration and winter rainfall.The total soluble salts,chloride and sodium ions,appeared to be higher in the 60-90cm horizons than other horizons in the soil profile due to repeated accumulation and leaching and the low permeability of clay horizon.The sodium adsorption ratio (SAR) of the soil and the salt concentration of the white clover shoots increased with the soluble salt concentration of irrigation water.Pasture yield was not significantly affected by irrigation water with a salt concentranon up to 1500mg/L and only reduced by about 9% to 17% at the salt concentration of 3000mg/L under different irrigation conditions.It is evident that irrigation management could play a certain role in regulating salt-water dynamics of soils.
Chen Enfeng , Zhou Likai , Wu Guanyun
Abstract:Based on many-year researches on black soil and brown soil,different performances of various fractions of soil microaggregates in storing and supplying moisture and nutrients are discussed.In vlew of the significant differences of these perforrnances between fertile and infertile soils and between small and large sizes of microaggregates,the authors attempt to take 10μm as alimit,puling various fractions of microaggregates under
Abstract:This paper deale with the chemical composition of organic and inorganic components and their combined characteristics in G1 and G2 organo-mineral complexes.It was found that iron tended to accumulate in G2 fraction.The contents of free Fe and Al oxides were higher in G2 than in G1 in all soil samples.The loosely combined humus(H1) was more in G1 than in G2,but an opposite trend existed for tightly combined humus (humin).A little differences of the ratios of loosely combined humus to stably combined humus(H1/H2) and humic acid to fulvic acid(HA/FA) were observed between G1 and G2 fractions in most of the soil samples.Both G1 and G2 fractions contained some complex Fe,AI and Ca.It was concluded that the total amount of humus and humin of G2 was higher than that of G1,but G1 and G2 organomineral complexes could not be regarded as Ca-combined and Fe and Al-combined complexes,respectively.
Ma Chengze , Zhou Qin , He Fang
Abstract:This paper reports the surplus-deficit distribution of organic carbon (0.C.) in soil obtained through a 4-year field experiment with different treatments of fertilization.Results show that there was severe deficit in the balance of soil organic carbon without fertilization,which caused the produce of loosely combined organicmineral complexes and lowly condensed humus.Application of chemical fertilizer alone temporarily kept higher productivity of soil and lost not much of organic carbon in soil.The loss of O.C.under this condition mainly came from the appearance of the stably and tightly combined organic-mineral complexes and highly condensed humus.Even though there was a decrease of total soil O.C.,because of the compensation of crop residues naturally returned to field,there still was surplus of loosely combined O.C.little loss of fulvic acid and a great loss of humic acid and humin were observed in this case.It seems that fertilizer actually promoted the renewal of soil humus and resulted in less undesirable influence on soil complex and nutrient-supplying ability in a short time.There was surplus balance of soil O.C.in field when organic materials were combined with chemical fertilizers.Large amount of manure applied in field made the surplus O.C.almost averagely distributed among loosely,stably,and tightly combined complexes.However,the increase of soil O.C.still could not markedly improve the activity of humus.The accumulation of O.C.was mainly in the form of fuvic acid distributed among loosely combined organicmineral complexes when straw was added.This promoted the activity and cycle of soil humus,and enhanced the property of nutrient supply capacity.
Shi Jianwen , Bao Shidan , Shi Ruihe
Abstract:The potassium release characteristics and fixation abilities of five soils were studied by using depletion experiments and soil incubation experiments.The results were summarized as follows: With the extensive root systems ryegrass could draw up much of potassium from the soil potassium pool with in a short time.During the exhaustion cropping the soil deficient in potassium would quickly reach the lowest potassium value.In general,the lowest value of exchangeable potassium occurred at second harvesting and that of nonexchangeable potassium was obtained at third cutting,the lowest value changed with the tune of clay minerals.Potassium absorbed by plants mainly came from the soil interlayer potassium,among this,the potassium which could not be extracted by boiling with lmol/L HNO3 was dominant.The more the soil K depleted,the more the applied potassium fized by soil.Under different water conditions,the amount of fixation of fertilized potassium was in the order of alternative dry and wet>constant wet>submerged.
Abstract:The present paper deals with a systematical investigation of vanadium contents in main soil types of China.The results are summarized as follows:1.The total vanadium content of the main soils in China ranged from 9 to 266μg/g,averaging 86μg/g.Parent materials was the decisive factor affecting the total vanadium contenss.For instance,in red earths different in the parent materials,the total vanadium content was in the sequence of the red earth derived from basalt>that from phyllite>that from Q2 red clay>that from granite>that from limestone>that from Tertiary red sandstone>that from rhyolite.2.In general,total vanadium contents and soluble vanadium contents of soil profiles were not consistent.It is revealed that they could be accumulated or enriched in surface soil or subsoil,and in some conditions,they could be distributed in homogeneous state.3.Total iron content of soil was one of the most important factors affecting distribution and mobilization of vanadium in soils.Vanadium in soils as largely combined closely with iron oxides,except amorphous iron oxides.The soluble vanadium as combined with amorphous iron oxides in soils.
Wu Qitang , J. L. Morel , A. Guckert
Abstract:The paper put forward a coupled mathematical model of element desorption,transfer and root uptake of heavy metals in soilplant systems,and gives the theoretical quantitative relationships between the plant uptake,on the one hand,and soil solution concentration,soil buffer power,diffusion coefficient,total root length,average radius,water transpiration and growth time on the after.The pot experiments showed that the calculated uptake with this model was highly correlated with the actual uptake of cadmium by ryegrass,and the model could be used to predict rather well th0 effective uptake.
Chen Yingxu , Luo Yongming , Zhu Yongguan , Zhu Zuxiang , He Zengyao
Abstract:Cr(Ⅲ) removal in solutions with different pH values was measured under conditions of adding and without adding soils and minerals.With pH increasing in soil solution,the amounts of Cr(Ⅲ) removal by adsorption and precipitation increased when pH<10.5,but decreased when pH>10.5.The curve of Cr(Ⅲ) removal by soils and minerals could be divided into four ranges:(1)pH range of Cr(Ⅲ) adsorption when pH
Abstract:Mangrove and acid sulphate soils developed from mangrove swamp are about 106,000 ha in China.One of the main characteristqcs of mangrove is the high S content in its chemical composition (generally 0.2%-0.6,0.4% on average,much higher than the 0.1% of tropic shrub).The characteristic greatly influences the genests and nature of the soils.When the remains of mangrove are buried and decomposed,a large amount of S enters the soil,making the kind of soil contain the buried mangrove layer with a high S content.In general,the surface soil is about 0.2% in the content of total S,and the buried mangrove layer is mostly over 0.3%,while other acid soils of tropic region are only about 0.04%.Besides,SO42- content of the underground water in this kind of soil is 10-20 times as much as that of the sea waters of estuary.And it can also prove that S of the soil chiefly comes from the S of sea water accumulated by mangrove.After the swamp is enclosed and reclaimed,the soil water goes off.Sulphides produce a large amount of sulphate due to oxidization,so the soil reveals strong acidity-the lowest pH can reach 2.2,and lots of Al are activated and separated out.This is very harmful to the growth of plants.We consider the buried mangrove layer (the S-bearing horizon) as the diagnostic horizon (total S is 0.3% or higher; the pH of dried soil is 3.8 jarosite color value is ≥2.5 Y) and sub divide the soil into three types according to the appearing dep;h of the horizon: the shallow(<25cm),the middle (25-45cm) and the deep (45-70cm).
Xing Baoshan , M. J. Dudas , Zhang Zhiyi , Xu Qi
Abstract:With the study of physical,chemical,morphological and mineralogical properties of three pedons of typical albic soils from the Three River plain of Heilongjiang Province,we discussed the pedogenetic characteristics.The profiles were found to be lithologically countinuous by the comparsion of Zr/Sr and Ti/Zr ratio within the pedons.The albic soils study was characterized by a mollic epipedon,an ablic E horizon and a thick argillic horizon.Through this study,it was indicated that lessivage was a dominant pedogenetic process.Pedogenic Fe Mn nodules were found abundant in Ah and E horizons and were apparently forrned by weathering of Fe-Mn primary minerals,and the nodules may have developed in situ.The maximum amounts of pyrophosphate extractable Fe and AI appeared it Bt2 horizons were smaller than the values required for podzols.Vermiculite,which had not previously been recognized,dominated the clay fraction of albic soils.The clay mineral assemblage was qualitatively similar but quantitively differentiated throughout the profile.Finally,we suggested that the albic soils could be classified as mollie planosols in the FAO-UNESCO system and Typical Argialbolls in Soil Taxonomy.
Abstract:石灰性土壤是大面积缺锌土壤的主要类型[1],碳酸盐是影响石灰性土壤锌有效性的重要因子,主要是由于其作为石灰性土壤吸附固定锌的主要基质1)对土壤锌的强烈吸附固定作用,使土壤有效锌减少所致。关于土壤锌的吸附作用,特别是碳酸盐对土壤吸附锌的影响及其相互关系等已有较多研究[2-7],土壤锌的解吸研究有零星报道[3,6,7],而直接涉及碳酸盐对土壤锌解吸及有效性的影响研究尚未见报道,本文通过一组试验,重点研究碳酸盐(主要是碳酸钙)对土壤锌解吸的影响,探讨碳酸盐与土壤吸附锌的释放及有效性的关系。
Xu Junxiang , Tang Yongliang , Xu Yongfu
Abstract:我国南方红壤为严重的缺硼土壤,有99%的红壤样品水溶性硼含量低于0.5μg/g的临界含[1]。施用石灰是酸性土壤上的重要技术措施,施用石灰提高了土壤pH,同时增加了土壤中钙含量,过量的施用石灰会降低硼的有效性。Fox(1968)[5]发现硼的吸收机制受着高浓度Ca2+和OH-的影响,Jones[4]认为植物应保持合理的钙硼比值,以求平衡。本文讨论在红壤上不同氮肥水平下施用石灰和硼对油菜籽产量的影响和体内钙硼平衡的状况,探索合理的钙硼比值,以期达到提高产量的目的。