摘要:

An accurate estimate of nitrogen (N) mineralized during the growing season is needed for agronomically and environmentally sound N fertilizer recommendations. The objective of this study was to evaluate mineralization potential (No) of the predominate soil series in the Saginaw Valley and Thumb region of Michigan with the goal of utilizing this information to formulate N fertilizer recommendations. Air‐dried samples representing 17 sites were incubated and NO3and NH4produced were measured periodically. These data were used to determine N‐mineralization potential (No) utilizing exponential and hyperbolic models. The initial hypothesis for this study was the existence of a unique Novalue for each soil series. If this were the case, then this measurement could be used to formulate soil series specific N recommendations. Results show there is as much variability in Novalues within soil series as between soil series. Consequently, utilizing a single Novalue for a soil series in formulating N recommendations is not practical.

ISSN:0010-3624    

DOI:10.1080/00103629809370116

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Production of methane gas from coal seams generates well water that is slightly to moderately saline. Since land application is a potential method of disposal for this water, a greenhouse study was conducted to evaluate plant response and changes in soil chemical properties resulting from irrigation with coalbed methane‐produced water. The soil was a Montevallo (Typic Dystrochrepts)‐Nauvoo (Typic Hapludults) association located in northern Alabama. Two irrigation methods used in the initial greenhouse test were 1) continuous, irrigation 24 h d‐1and 2) intermittent, irrigation for 12 h and off for 24 h. In a second greenhouse test, three irrigation methods were used: 1) continuous, irrigation for 24 h d‐1, 2) intermittent, irrigation for 12 h and off for 48 h, and 3) irrigation to maintain field capacity, by daily additions of the respective irrigation water. The flow rate for continuous and intermittent irrigation treatments was 3.75 mm h‐1. In each greenhouse test, 5 levels of salinity were generated by mixing well‐produced water with deionized water to give solutions containing 0, 10, 20, 40, and 100% well‐produced water (specific conductance (second greenhouse test) of 0.2, 1.4, 2.2, 4.4, and 9.3 dS m‐1, respectively). Corresponding sodium adsorption ratios were 0.1, 27, 36, 55, and 81, respectively. Sorghum‐sudangrass [Sorghum bicolor(L.) Monech] was harvested for forage yields and chemical analysis at 14–30 days after initiation of irrigation treatments. Results from these preliminary short term, greenhouse studies show that coalbed methane produced water that is typical for Alabama (total dissolved solids ≤2000 mg L‐1) can be applied to highly weathered soils. The results indicate that plant growth of summer annual grasses will be optimized if an irrigation system is used to apply produced water at a rate to maintain soil moisture at or near field capacity.

ISSN:0010-3624    

DOI:10.1080/00103629809370117

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The combination of cropping rotation and tillaging for several years have altered the distribution of nutrients such as phosphorus (P) and potassium (K) in the soil profile. These long‐term changes have led researchers to investigate the distribution of nutrients and the distribution of roots in alternate cropping and tillage systems. The purpose of this study was to clarify if and how interactions between tillage systems and crop rotation, in long‐term plots, affected P and K distribution and root development, in the soil profile. This continuous long‐term tillage study consisted of 8 treatments arranged in a randomized split‐plot design and replicated three times. It consisted of one rotation treatment, corn(Zea maysL.) And soybean [Glycine max(L.) Merr.] and of continuous corn as the main plot. Three primary tillage operations (fall moldboard plow, fall chisel, and no tillage) were tested as subplot. We found a greater concentration of P in the upper layers of the soil regardless of the tillage system. The P stratification was characterized in no‐till system as a result of a surface applied fertilizer without incorporation. Potassium concentration in the soil surface decreased in depth in the chisel and in the no‐till treatments, presumably as a consequence of the fertilization. Phosphorus stratification stimulated root growth in conservation systems when compared to the conventional one.

ISSN:0010-3624    

DOI:10.1080/00103629809370118

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

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‐1did 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.

ISSN:0010-3624    

DOI:10.1080/00103629809370119

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A single‐channel flow injection system was optimized for the determination of available iron (Fe) in soil extracts by atomic absorption spectrophotometry. This method of introducing the samples in the spectrophotometer worked particularly well in preventing blockage of the burner head which was observed in the conventional introduction of Fe for its determination by atomic absorption spectrophotometry. The appropriate selection of the manifold parameters, such as injection volume, tube length and flow rate, allowed introduction of any soil extract without requiring any pre‐treatment. This system allowed determinations at a detection limit of 0.36 mg L‐1to 5 mg L‐1, with an output of 300 determinations per hour. The results obtained for analysis of 15 soil extracts were in good agreement with those provided by the colorimetric method, with average relative deviations of 1.6%. Relative standard deviations of 4.8, 2.5, and 2.3% were obtained for contents of 1.03, 1.85, and 3.99 mg Fe L‐1, respectively.

ISSN:0010-3624    

DOI:10.1080/00103629809370120

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Sokoto rock phosphate (SRP) obtained from Sokoto in the Northern Nigeria was evaluated with some other phosphorus (P) sources viz: Partially acidulated rock phosphate (PARP) and single superphosphate (SSP) in the greenhouse and field studies. These fertilizers were also compared with nitrogen‐phosphorus‐potassium (NPK) 11–12–11–9.7S‐1.4Zn and NPK 10–20–5–6.5S which have 80% of their P as rock phosphate and were formulated through compaction. The fertilizers were applied in the greenhouse at 0–400 mg kg‐1soil on the Oyo Arenic Haplustalf and Alagba Kandiudult soil. Field trials were carried out at four locations—at Ikenne in the humid, Samara in the subhumid, Gumi and Gusau in the semi‐arid zones of Nigeria. The fertilizers were applied at 0–150 kg P2O5ha‐1in the humid zone and 0–100 kg P2O5ha‐1in the subhumid and semi‐arid zones. Maize was used as test crop in most sites except at Samaru where sorghum was planted. The results of the greenhouse study showed that on the Haplustalf, PARP, and NPK 10–20–5–6.5S gave almost a similar relative agronomic effectiveness (RAE about 70%) as SSP, which was followed by SRP and NPK 11–12–11–9.7S‐1.4Zn (RAE between 50 and 60%). On the Kandiudult, the RAE of the fertilizers increased significantly. The PARP and NPK 10–20–5–6.55S gave high effectiveness (RAE about 90%) relative to SSP. The field trials results indicated that ground SRP was suitable for direct application on slightly acid soil in the humid zone (annual rainfall > 1,200 mm). Its efficiency was fairly moderate in the subhumid and quite low in the semi‐arid zones (annual rainfall <900 mm). The PARP gave higher RAE than SRP and had almost similar efficiency as for NPK 10–20–5–6.5S. The PARP was well comparable to SSP in the humid and subhumid zones and was fairly comparable to the later in the semi‐arid. This suggests that PARP may be suitable for humid and subhumid zones and the physical quality was also superior to SRP and SSP. Application of SRP on soils in the semi‐arid zones of low rainfall gave relatively low yields which could be due to inadequate moisture availability required to enhance P solubilization.

ISSN:0010-3624    

DOI:10.1080/00103629809370121

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Soil phosphate in solution (PsolCpand equilibrium P concentration (EPCo) are important soil P parameters both for agronomical and environmental purposes. Solution P is the main source from which plant roots adsorb P, whereas EPCo give information about the amount and direction of changes between soluble and particulate P that occur during transport of sediment in stream flow. Changes inPsoland EPCo with soil extractable P (Mehlich 3‐P and Olsen P) were determined following equilibration of 13 Italian soils with five rates of fertilizer P (0 to 100 mg kg‐1). The slope of the regression equation (Y=a+bX) for the relationships between Psoland EPCo (Y), and soil extractable P (X) decreased with increasing soil P sorption. Furthermore, at the same level of Mehlich 3 and Olsen P, higher sorbing P soils had lower values of Psoland EPCo. As a result, changes in Psoland EPCo per unit increase of soil extractable P were closely related (R2of 0.86 to 0.93) to soil P Sorption Index (SI). Equilibrium P Concentration could be estimated from soil solution P for the studied soils.

ISSN:0010-3624    

DOI:10.1080/00103629809370122

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The charge properties of three soils developed on granulite and serpentinite were investigated. These soils contain large amounts of organic matter, free iron oxide, and clay, and are therefore a good medium for measuring the interactions between those components. Cation‐ and anion‐exchange capacities (CEC and AEC) were measured in percolation experiments with and without ammonium acetate buffer pretreatment, using various electrolyte concentrations. The measurements were repeated after removal of sesquioxides and/or organic matter. In addition, potentiometric titrations were carried out to determine the ‘point of zero salt effect’ of each sample. Untreated samples showed a mutual blocking of positive charge on sesquioxides and negative charge on organic matter, leading to decreased CEC and negligible AEC values. Because the AEC is fully blocked, the natural soils do not have a ‘point of zero net charge’ (PZNC), and the apparent ‘points of zero salt effect’ (PZSE) obtained in potentiometric batch titrations are artifacts. Positive charge appeared only after the removal of organic matter. Percolation with acetate buffer strongly increased the measured CEC in samples containing organic complexes. After removal of organic matter, a slight buffer effect remained. This is attributed to the release of sesquioxides from organic complexes and clay surfaces by preferent binding to the acetate anion.

ISSN:0010-3624    

DOI:10.1080/00103629809370123

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Nitrogen use efficiency (NUE) of N fertilizer can be accurately estimated by tracing the fate of soil applied15N‐labeling. However, the quantity of N remobilization from non‐kernel components into kernels in maize (Zea maysL.) plants is difficult to determine. A field experiment involving stem infusion with four levels of enriched15N solution plus non‐infusion or infusion with water was conducted at Ottawa (45°22'N, 75°43'W), Canada to determine the effect of15N atom % enrichment (a.e.) on physiological processes associated with NUE. At anthesis, 30 mL of 35.7 mmol N solution as15NH415NO3at 5.0 (N05), 33.0 (N33), 66.0 (N66) and 99.2 (N99)15N% a.e. was infused into the internode below the primary cob. The control plants were infused with distilled water. Photosynthesis was measured at 2, 4, 6, 24 h and 1 wk after infusion. Plants were sampled and separated into components at 4 d after anthesis (D4A) and at physiological maturity (PM). Dry weight, total N concentration, NH4‐ and NO3‐N, and15N% a.e. of each component were determined. At D4A, the N33 and N66 treatments resulted in component15N enrichment similar to that of N99 treatment. At PM, however, only N66 treatment produced results similar to that of N99. None of the infused15N treatments interfered with ear‐leaf photosynthesis or component NH4‐ and NO3‐N concentrations. Infused15N was easily moved out of the internode where it was infused, into most components, with the majority in the dominant sinks (cob, husk, and kernels). Nitrogen remobilization in both N66 and N99 treatments accounted for 62% of kernel N. These findings indicate that stem infusion is an appropriate approach to study N remobilization. Based on the concentrations investigated in this study, 66% or higher15N% a.e. is required for accurate labeling when soil available N is high.

ISSN:0010-3624    

DOI:10.1080/00103629809370124

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Paddy soils of over 500 hectares had been polluted by arsenic (As) from tailings at an abandoned lead‐zinc mine at Shaoxing, Zhejiang, China. Several field experiments were conducted to establish measures for reducing As toxicity to rice plants. The results obtained were as follows. Fresh Chinese milkvetch (Astragalus sinicusL.) was not supposed to be used as green manure in arsenic polluted paddy soils. Although liming (1,500 kg CaO hectare‐1) could reduce water‐soluble As (H2O‐As) in the soil, the rice plant grew badly. The treatments of FeCl3(25 mg Fe kg‐1soil) and MnO2(25 mg Mn kg‐1soil) could markedly lower the H2O‐As and arsenite [As(III)] percentage in the soil and make the plant grow better than the control experiment (CK). Without adding any materials to the soil, wetting and drying (furrowing and draining) in the paddy soil could increase soil redox potential greatly and lower the H2O‐As and As(III) percentage obviously leading to better rice growth. In addition, the As contents of roots, flag leaf, grain, and husked rice of 11 new cultivare of early rice were determined and correlation analysis was conducted. Uptake and accumulation of As in different parts of cultivars Zhefu‐802 and Erjiufeng at the 4 As levels of the paddy soil demonstrated that the As contents in husked rice of both cultivars exceeded the hygienic standard (0.7 mg As kg‐1) when they grew in the paddy soil having total As content of about 70 mg kg‐1for Zhefu‐802 and 100 mg kg‐1for Erjiufeng, respectively.

ISSN:0010-3624    

DOI:10.1080/00103629809370125

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor