巴西南部氧化土长期施用猪粪粪浆对土壤和地表水的影响

The accelerated expansion of swine production in Brazil has increased the generation of liquid wastes, which are usually applied to agricultural soils after a simplified treatment and pose potential environmental impacts. The objective of this study was to assess the agronomic and environmental impacts of long-term application of swine slurry(SS) on soil and stream water properties in watersheds dominated by Oxisols in Quinze de Novembro of Southern Brazil. Soil samples(0–30 cm) were collected from farms with continuous application of SS since 1990 at low(40–80 m3 SS ha-1year-1) and high(120–300 m3 SS ha-1year-1) rates of SS. Surface water samples were collected from streams adjacent to the farm fields. Long-term SS application did not change total organic C and particulate organic C compared to cropland and woodland soils without SS application. The high rates of SS increased total N, P, Cu,and Zn and available P and Cu in the topsoil(0–10 cm) compared to woodland and cropland soils without SS application. Surface water analyses showed that fecal coliform bacteria and biological oxygen demand exceeded the legal limits for high quality water(Class 1). Other water parameters(such as NO-3, phosphate and total suspended solids) were within the acceptable limits. Long-term disposal of SS in cropland under no-tillage had impaired water quality in Quinze de Novembro, especially biological parameters. Some best management practices should be adopted, including more rigorous control of SS application to cropland as well as requiring edge-of-field and riparian vegetative buffers.     

长期施肥对潮土耕层土壤和作物籽粒微量元素动态的影响

Micronutrient status in soils can be affected by long-term fertilization and intensive cropping.A 19-year experiment (1990-2008) was carried out to investigate the influence of different fertilization regimes on micronutrients in an Aquic Inceptisol and maize and wheat grains in Zhengzhou,China.The results showed that soil total Cu and Zn markedly declined after 19 years with application of N fertilizer alone.Soil total Fe and Mn were significantly increased mainly due to atmospheric deposition.Applications...     

氮肥用量和水分淋溶对土壤和小麦氮素平衡的影响

:利用标记15N尿素研究不同施肥量和淋溶对小麦生长的影响 ,结果表明水分淋溶对小麦生长的影响不明显 ;地上部生物产量与肥料利用率成正相关 .小麦根系越发达 ,收集到的淋溶液越少 ,损失的肥料N越少 .施用相同量的氮肥 ,淋溶处理的氮肥利用率略低于正常浇水的处理     

Effects of three soil tillage systems on some biological activities in an Ultisol from southern Chile

Intensive tillage for annual crop production may be affecting soil health and quality. However, tillage intensity effects on biological activities of volcanic-derived soils have not been systematically investigated. We evaluated the effects of three different tillage practices on some biological activities of an Ultisol from southern Chile during the third year of a wheat–lupin–wheat crop sequence. Treatments were: no tillage with stubble burning (NTB), no tillage without stubble burning (NT) and conventional tillage with disk-harrowing and stubble burning (CT). Biological activities were evaluated in winter and summer at 0–200 mm and at three soil depths (0–50, 50–100 and 100–200 mm) in winter. Total organic C and N were significantly higher under no-tillage systems than CT. In general, NT increased C and N of microbial biomass in comparison with CT, especially in winter. Microbial biomass C was closely associated with microbial biomass N (r = 0.986, P < 0.05); acid phosphomonoesterase (r = 0.999, P < 0.05); β-glucosidase (r = 0.978, P < 0.05), and others. Changes in biological activities occurred mainly in the upper soil layer (0–50 mm depth) in spite of the short duration of the experiment. Biological activities could be used as practical biological indicators to apply the more appropriate management systems for increasing soil sustainability or productivity.     

Effects of tillage systems on soil characteristics, glomalin and mycorrhizal propagules in a Chilean Ultisol

Tillage affects the soil physical and chemical environment in which soil microorganisms live, thereby affecting their number, diversity and activity. However, soil disturbance generally has the greatest impact on biological properties, including both free and symbiotic fungal populations. Interest in more ecologically sustainable agricultural systems is rising with increasing recognition that agricultural intensification can adversely affect environmental quality. This paper discusses the effect of tillage system on some soil characteristics, such as pH, C, N and S levels, total and Olsen-P contents including some P forms associated with organic matter, glomalin contents and arbuscular mycorrhizae (AM) parameters, such as root colonization, spore number and total and active hyphal length. Measurements were in the sixth year of an on-going tillage-rotation experiment conducted on an Ultisol under no-till (NT), reduced tillage (RT) and conventional tillage with stubble mixed into the soil (CTS) or stubble burnt (CTB). Soil was sampled at two dates; after wheat (Triticum aestivum) harvest (autumn) and 6 months after subsequent grassland seeding (spring). Higher C, N, S, total P and fulvic acid-P concentrations and pH occurred under NT and RT than under CTS and CTB after wheat harvest. However, results at the second sampling were not consistent. AM spore number and active hyphal length were highest under NT having the greatest incidence on AM root colonization and P concentration in shoots of the pasture. Glomalin concentration was higher under NT and RT than under CTS and CTB but no differences in calculated glomalin to total C (ca. 5%) were found. It is concluded that a less disruptive effect of NT influences positively all soil characteristics and also increases P acquisition by the following crop in the rotation system.     

Seed quality of runner peanuts as affected by gypsum and soil calcium 1

There is only weak evidence that supplemental soil Ca may be beneficial beyond its obvious effects on yield and sound mature kernel (SMK) of runner peanuts (Arachis hypogea L.). This study was initiated to determine the effect of applied Ca on seed Ca, seed germination, and seedling vigor on sites varying in extractable soil Ca and to determine the minimum seedCa concentration required for maximum germination and seedling vigor of runner peanuts. Eight on‐farm experiments with replicated gypsum and no‐gypsum treatments were established on soils with 130 to 625 mg/kg Melich‐1 extractable Ca. Yield and SMK were generally unaffected by the gypsum topdressing, but there were effects on seed concentrations of Ca, Mg, and K. One site showed a highly significant increase in germination and seedling vigor from the gypsum application and two other sites had a significant increase in seedling survival without a simultaneous increase in germination. The minimum seed Ca needed for maximum germination was 282 mg/kg, while the minimum needed for maximum seedling survival was 260 mg/kg. The data suggest that a higher level of available soil Ca is needed for maximum seed quality than is needed to obtain maximum yield or SMK.     

不同培肥方式黑土腐殖质形态特征研究

针对吉林省黑土区存在的土壤有机质下降、耕地质量退化等问题,利用公主岭国家黑土肥力与肥料效益监测基地连续20年的长期定位试验,采用核磁共振波谱分析法(NMR)、红外光谱分析法(IR)等现代分析方法,研究了不同培肥途径耕层土壤腐殖质的组成、形态结构及动态变化趋势。结果表明:不同培肥途径对耕层土壤腐殖质特征影响明显。施用玉米秸秆处理(S+NPK)和施用有机肥+轮作处理(M+NPK+R)均显著增加了土壤胡敏酸中脂肪族结构成分,单施有机肥处理(M+NPK)显著增加了土壤胡敏酸中羟基含量,S+NPK处理游离羧基含量显著增多。S+NPK、M+NPK及M+NPK+R处理,土壤富啡酸的甲基、亚甲基和次甲基结构成分显著增多,游离羧基含量也显著增多。单施化肥处理,浸提的富啡酸中无机碳酸盐和硅酸盐成分明显增多,化肥长期施用导致土壤中游离富啡酸数量显著减少,土壤的耗竭式利用,导致土壤中铁、铜结合态或络合态的富啡酸增加。不同培肥方式对黑土胡敏酸和富啡酸的元素组成影响有较大的差异,但均可引发胡敏酸C含量降低,N含量增加,富啡酸C、N、H含量增加,O含量降低,可通过不同的培肥方式对土壤腐殖质的元素组成进行调节。     

Cadmium fractions in an acid sandy soil and Cd in soil solution as affected by plant growth

In a previous experiment, plants were able to immobilize or solubilize Cadmium (Cd) in a sandy acid soil enriched with 40 μmol Cd kg^–1, because Cd solution concentration was decreased by maize (Zea mays) and sunflower (Helianthus annuus), and increased by flax (Linum usitatissimum L. ssp. usitatissimum) and spinach (Spinacia oleracea). It is assumed that the equilibrium with Cd fractions in the soil solid phase and the chemical form of Cd in the soil solution were affected. In the present study, the effect of the four plant species mentioned above on Cd binding in soil was investigated by means of a fractionation of soil Cd with a sequential extraction of seven steps. The seven fractions of Cd are operationally defined by the extraction sequence that follows the order of increasing acidity with extractants of different complexing and redox properties. In the unplanted soil, Cd was predominantly present in the exchangeable Fraction I (F. I) and easily mobilizable Fraction II (F. II) (64%). Significant concentrations of Cd were found in F. III (occluded in Mn oxides; 22%) and F. IV (organically bound; 10%). Fractions V (occluded in poorly crystalline Fe oxides), F. VI (occluded in well crystallized Fe oxides), and F. VII (residual fraction) amounted to less than 5% of the total soil Cd concentration. The plants changed the binding of Cd in soil in a different manner. All plants decreased F. I, but F. II was increased by maize and spinach, decreased by flax or remained unaffected by sunflower. Fraction III was not affected by maize and flax, but decreased by sunflower and spinach, and F. IV was not affected by sunflower and spinach, but was increased by maize and flax. These changes of Cd fractions were not related to the changes the plants had caused in total Cd or Cd²⁺ concentration of the soil solution. These results show that plant species differ in how they affect Cd binding to the soil solid phase, but this effect is not related to how they affect Cd in soil solution. The mechanisms by which plants affect the relationship between the soil solid and liquid phase are still unclear.     

Potassium uptake by soybean as affected by exchangeable potassium in soil

Abstract

Soybean (Glycine max (L.) Merrill) has been shown to have a great capacity to take K from soil, suggesting that it might absorb K from non‐exchangeable forms. In this paper, the effect of level of K fertilization on soil exchangeable K content and K uptake by soybean are discussed. The experiment was conducted on a Typic Haplortox (sandy loam), fertilized with 0, 40, 80, 160 and 240 kg K₂O/ha as KC1 or K₂SO₄. During five years before the experiment, half of the plots received those K rates annually and the other half only in the first three years, providing an opportunity to study the residual effect of applied K. Plant samples were taken at pod filling and at harvest. Soil cores were collected in 20 cm increments down to 80 cm deep at plant emergence, pod filling and after harvest. There was a residual effect of K, and 240 kg K₂O/ha applied in a 3‐year term led to the same yield and K uptake as 80 kg ICO/ha applied annually for 3 years. Fertilized plants absorbed 160% more K than unfertilized ones, but soil exchangeable K accounted for less than 50% of plant uptake; therefore the exchangeable pool must have been replaced in time for soybean uptake. On the other hand, the K recycled from the plant to the soil was not found in the exchangeable form. There was evidence of K leaching deeper than 80 cm, and in addition, the K recycled from the plants may have turned into non‐exchangeable forms in the soil.     

Morphology and distribution of wheat and maize roots as affected by tillage systems and soil physical parameters in temperate climates: an overview

Congregated information on maize and wheat root morphology and their distribution as influenced by tillage and soil physical conditions is meager. Root growth under no-tillage (NT) or conventional tillage (CT) is variable: Under NT, higher bulk density slows root elongation and provides shorter roots but simulate root branching; results may be opposite depending on soil texture. Under CT, soil compaction may have negative effects on root growth, with roots exhibiting plasticity. In humid climates, low soil temperatures can reduce root length density (RLD) and increase the diameter of spring cereals under NT. Tillage intensity induces a different distribution of nutrients, a trend which increases with time resulting in higher RLD in the topmost layer of NT. Compared to maize it is difficult to present an overview of the effect on tillage on the RLD of wheat due to inconclusive results. Adequate placements of banded starter fertilizer will effectively build up an early root system of maize, especially at suboptimal growth temperatures. Many studies reported a higher or similar grain yield of maize or wheat under NT compared to CT in temperate climates. However, the limited information or the conflicting results will promote the topic for inclusion in future breeding programs.     

Determination of extractable sulfate and total sulfur from plant and soil material by an autoanalyzer

Abstract

The method has been modified from Sinclair^3,4 and tested for extractable sulfate and total sulfur on plant, soil, and water samples. Inorganic sulfur is extracted from plant and soil material by using dilute acidic extractants, and total sulfur is estimated from dry ashed or wet ashed material whereby various sulfur forms are oxidized to sulfate‐sulfur. The sulfate is precipitated in sample solutions as barium sulfate and determined turbidimetrically by AutoAnalyzer.

The method is rapid, precise, and sensitive enough to be used on a routine basis.     

Changes in chemical properties of an Ultisol as affected by palm oil mill effluent application

Abstract

An experiment was conducted to determine the effects of palm oil mill effluent (POME) application on soil chemical properties. The POME was incorporated into the top 0–30 cm of Batang Merbau soil, an Ultisol. POME was applied at 0, 5, 10, 20, and 40 t ha^‐1, both in the presence and absence of 2 t ground magnesian limestone (GML). A succeeding crops of maize and groundnut were planted. The results of the experiment showed that POME application up to the rate of 40 t ha^‐1 did not significantly change the topsoil pH and exchangeable calcium (Ca), magnesium (Mg), and aluminum (Al). The addition of POME improved the soil fertility, which resulted in an increase of maize yield. The Ca and Mg from the POME accumulated in the topsoil, being held by the negative charge present on the exchange complex. The beneficial effects of POME and/or GML application lasted for about 3 years. The study indicated that application of POME together with GML is a good agronomic option to alleviate soil acidity in Ultisol for maize production.     

Zinc in wheat grain as affected by nitrogen fertilization and available soil zinc

Greenhouse and field experiments were conducted to determine the influence of nitrogen (N) fertilization and DTPA‐extractable soil zinc (Zn) on Zn concentration in wheat (Triticum aestivum L., cv. Pioneer 2375) grain. Application of zinc sulfate (ZnSO₄) in the range of 0 to 8 mg Zn kg^‐1 increased linearly DTPA‐extractable Zn in an incubated calcareous soil from 0.3 to 5.0 mg kg^‐1. Application of these rates of ZnSO₄ to the same soil under greenhouse conditions increased Zn concentration of wheat grain from 26 to 101 mg kg^‐1. The influence of 134 kg urea‐N ha^‐1 on Zn concentration in wheat grain at eight field sites, with DTPA‐extractable soil Zn levels ranging from 0.3 to 4.9 mg kg^‐1, was studied. Nitrogen fertilizer increased wheat‐grain yields in four of the eight experiments but had little effect on grain‐Zn concentration. Grain‐Zn concentration ranged from 31 to 45 mg kg^‐1 in N‐fertilized plots at the various sites and was related (r=0.74*) to DTPA‐extractable soil Zn.     

Wet aggregate stability as affected by excess carbonate and other soil properties

Aggregate stability is a fundamental property influencing soil erodibility and hydraulic characteristics. Knowledge of soil components controlling aggregate stability is very important to soil structure conservation. The objective of this study, which was carried out in surface soils from central Greece, was to relate wet aggregate stability to selected soil properties, with emphasis on excessive free carbonate content. The wet‐sieving technique of air‐dried aggregates was used for structural stability evaluation, according to a test that calculates an instability index. The soils studied were developed on Tertiary marly parent material and ranged in calcium carbonate content from 5 to 641 g kg⁻¹. From the texture analysis before and after removal of carbonates, it was concluded that carbonates mainly contributed to total silt and sand fractions, that is to the mechanical fractions which, as a rule, negatively affect aggregate stability. The results of the correlation analysis showed that aggregate stability was positively affected by aluminosilicate clay content, cation exchange capacity (CEC) and Al‐containing sesquioxides. Clay fraction from carbonates and total sand and silt negatively affected aggregate stability. CEC has been proved a very significant determinant of aggregate stability, which in a hyperbolic form relationship with instability index explained 78·9 per cent of aggregate stability variation. Copyright © 2011 John Wiley & Sons, Ltd.     

喷灌施肥灌溉均匀性对土壤硝态氮空间分布影响的田间试验研究

在2002～2003年冬小麦生育期内进行了喷灌施肥条件下均匀系数对土壤水氮时空分布及淋失影响的田间试验。试验中,喷灌均匀系数设置低、中、高三个处理,灌溉季节内的平均喷灌均匀系数分别为72%、79%和84%,施肥灌溉均匀系数分别为71%、78%和85%。对70和90 cm深度处的土壤水势进行了监测以评估均匀系数对水氮淋失的影响,结果表明,在所研究的喷灌均匀系数范围内深层渗漏量很小。试验结果还指出,土壤硝态氮随时间和空间表现出很强的变化特征,均匀系数变化范围为23%～97%,变差系数的变化范围为0.04～1.00;灌溉季节内土壤硝态氮分布的均匀性主要取决于初始硝态氮分布的均匀程度,而喷灌均匀系数对土壤氮素的空间分布无明显影响。     

Crop yields and soil fertility as affected by dryland rotations in Southern Alberta

Abstract

Six of seven nonfertilized dryland crop rotations, consisting of combinations of fallow, wheat, alfalfa, and grass, have depleted several major plant nutrients in the soil in 20 years. The average contents of organic matter, total N, and exchangeable K were decreased by 14.5, 10.1, and 26.7%, respectively, in the 0‐ to 15‐cm soil horizon and by 24.1, 13.3, and 25.7% in the 15‐ to 30‐cm horizon. Total P content of the soils changed very little during 20 years of cropping. The amount of NaHC03‐extractable P decreased by 38.3% in the 0‐ to 15‐cm horizon of all soils except those in a manured fallow‐wheat‐wheat rotation, where a 30.6% increase occurred. Although soils were generally depleted, plant nutrients have not yet reached critically low levels, and therefore crop yields have been maintained at a fairly uniform level by using improved cereal varieties, timely tillage, good seedbed preparation, suitable seeding methods, and adequate in‐crop weed control. However, further depletion of plant nutrients from the soils will probably restrict crop production in the future. The results indicate that applications of adequate amounts of N, P, and K fertilizers, as determined by soil tests and correlative field tests, must be made to these and similar soils to ensure continued productivity.     

Dynamics of soil hydraulic properties during fallow as affected by tillage

There is limited information on the effects of tillage practices on soil hydraulic properties, especially changes with time. The objective of this study was to evaluate on a long-term field experiment the influence of conventional tillage (CT), reduced tillage (RT) and no-tillage (NT) on the dynamics of soil hydraulic properties over 3 consecutive 16–18 month fallow periods. Surface measurements of soil dry bulk density (ρ_b), soil hydraulic conductivity (K(ψ)) at −14, −4, −1 and 0 cm pressure heads using a tension disc infiltrometer, and derived hydraulic parameters (pore size, number of pores per unit of area and water-transmission porosity) calculated using the Poiseuille's Law were taken on four different dates over the fallow period, namely, before and immediately after primary tillage, after post-tillage rains and at the end of fallow. Under consolidated structured soil conditions, NT plots presented the most compacted topsoil layer when compared with CT and RT. Soil hydraulic conductivity under NT was, for the entire range of pressure head applied, significantly lower (P < 0.05) than that measured for CT and RT. However, NT showed the largest mean macropore size (0.99, 0.95 and 2.08 mm for CT, RT and NT, respectively; P < 0.05) but the significantly lowest number of water-conducting pores per unit area (74.1, 118.5 and 1.4 macropores per m² for CT, RT and NT, respectively; P < 0.05). Overall, water flow was mainly regulated by macropores even though they represented a small fraction of total soil porosity. No significant differences in hydraulic properties were found between CT and RT. In the short term, tillage operations significantly increased K (P < 0.05) for the entire range of pressure head applied, which was likely a result of an increase in water-conducting mesopores despite a decrease in estimated mesopore diameter. Soil reconsolidation following post-tillage rains reduced K at a rate that increased with the intensity of the rainfall events.     

长期施肥黑土微生物区系及功能多样性的变化

Black soil （Mollisol） is one of the main soil types in northeastern China. Biolog and polymerase chain reactiondenaturing gradient gel electrophoresis （PCR-DGGE） methods were used to examine the influence of various fertilizer combinations on the structure and function of the bacterial community in a black soil collected from Harbin, Heilongjiang Province. Biolog results showed that substrate richness and catabolic diversity of the soil bacterial community were the greatest in the chemical fertilizer and chemical fertilizer＋manure treatments. The metabolic ability of the bacterial community in the manure treatment was similar to the control. DGGE fingerprinting indicated similarity in the distribution of most 16S rDNA bands among all treatments, suggesting that microorganisms with those bands were stable and not influenced by fertilization. However, chemical fertilizer increased the diversity of soil bacterial community. Principal com- ponent analysis of Biolog and DGGE data revealed that the structure and function of the bacterial community were similar in the control and manure treatments, suggesting that the application of manure increased the soil microbial population, but had no effect on the bacterial community structure. Catabolic function was similar in the chemical fertilizer and chemical fertilizer＋manure treatments, but the composition structure of the soil microbes differed between them. The use of chemical fertilizers could result in a decline in the catabolic activity of fast-growing or eutrophic bacteria.     

Nitrous oxide emission as affected by changes in soil water content and nitrogen fertilization

Nitrous oxide emission was measured in laboratory incubations of an alluvial soil (58% clay, pH 7.4). The soil was amended with 40 mg N kg⁻¹ as NaNO₃ or NH₄Cl, or with NaCl as a control. Each fertilization treatment was adjusted to three different water contents: constant 60% WHC (water-holding capacity), constant 120% WHC, and water content alternating between 60 and 120% WHC. During an 8-day incubation period N₂O emission rates and inorganic nitrogen concentrations in soil (NH₄⁺, NO₂⁻, NO₃⁻) were determined at regular intervals. In the control and after nitrate application small N₂O emission rates occurred with only minor variations over time, and no differences between the water treatments. In contrast, with ammonium application N₂O emission rates were much higher during the first two days of incubation, with peaks in the constant 60% WHC and 120% WHC at day 1 and in the changing-water treatment at day 2, when the first wet period (120% WHC) was completed. This N₂O peak in the changing-water treatment was 4 to 9 times higher than with constant WHC and occurred when both, NH₄⁺ and NO₂⁻ concentrations declined sharply. Thus, this N₂O emission flush can be attributed to nitrifier denitrification. After the second rewetting of the NH₄⁺-amended soil no further N₂O emission peak was observed, being in accordance with small NH₄⁺ and NO₂⁻ concentrations in soil at that time. The unexpectedly small N₂O fluxes in the constant 120% WHC treatment after nitrate application were probably caused by the reduction of N₂O to N₂ under the prevailing conditions. It can be concluded that continuous wetting or flooding of a soil is an effective measure to reduce N₂O emissions immediately after the application of NH₄⁺ fertilizers.