摘要:

Surface mineable coal is abundant beneath many farmland areas in Missouri. Presently, 90% of the electricity generated in the state is by coal powered plants. Surface strip‐mining laws now require reclamation of these lands after drastic disturbance. Tall fescue (Festuca arundinanceaSchreb) cultivars and breeding lines have been evaluated for yield, nutrient composition and quality on undisturbed lands, but not for these qualities and for adaptability to revegetate drastically disturbed lands.

ISSN:0010-3624    

DOI:10.1080/00103628309367362

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Few references explain the effects of dry‐heat sterilization on soil chemical properties. Yet dry heating at 121°C for 2 hours is the prescribed USDA Animal, Plant, and Health Inspection Service basic treatment for soils entering United States ports of entry. This study concerns the effects of air drying and dryheat sterilization on chemical properties of Puerto Rican soils, chiefly macronutrients and micronutrients, found after extracting with Mehlich‐1 and Olsen solutions. Results for dry heating are compared with reported results for other sterilization procedures.

ISSN:0010-3624    

DOI:10.1080/00103628309367363

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Increasing soil bulk density has been shown to reduce root growth and decrease K uptake by soybeans (Glycine maxL. Merrill). Changing soil bulk density also affects soil buffer power, b, and effective diffusion coefficient, De, which affect K influx. The relative decrease in K uptake due to reduced root growth as compared to reduced K influx is not known. Addition of P may affect root growth and P influx properties of plant roots. The objectives of this paper were (1) to use the Cushman mechanistic model to simulate the effect of changing soil bulk density and soil P on K uptake by soybeans, and (2) to determine the parameters that are changed by changes in bulk density and added P and their effect on K uptake. Plant and soil data of an experiment where Williams soybeans were grown for 21 days in pots of Raub (Aquic Argiudoll) silt loam with factorial treatments of two rates of K (0 and 100 mg K kg‐1soil), two rates of P (0 and 100 mg P kg‐1soil), and two bulk densities (1.25 and 1.45 g cm‐3) were used to verify the model. Plant and soil parameters for the model were measured independently of the verification experiment. Predicted K (y) uptake agreed with observed uptake (x) (y = 1.09x‐0.19; r = 0.97) for the P x K factorial and (y = 1.19X‐0.22; r = 0.90) for the K x soil bulk density factorial treatments. In a sensitivity analysis, the model predicted a maximal K influx at a soil bulk density of 1.38 g cm‐3. The greatest effect of soil bulk density on K uptake was due to reduction of root growth. Increased K uptake as a result of P addition was because of the effect on root growth.

ISSN:0010-3624    

DOI:10.1080/00103628309367364

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Field experiments were conducted from 1970 through 1974 to determine the effects of intensive double‐cropping with notillage and conventional tillage on certain physical and chemical properties of a Huntington silt loam soil and a Pope silt loam soil. The soils were double‐cropped 4 years with corn and barley or oats. Three fertilizers rates were used. There were no significant effects at the 0.05 level on either bulk density or organic matter content. Soil pH in the surface 0 to 15 cm decreased and was related to the amount of N fertilizer applied. Soil test levels of P increased at each level of P fertilizer. The lowest level of K fertilizer was sufficient to maintain soil test K at its original value in the Huntington soil, but the medium level was necessary in the case of the Pope soil. Intensive double‐cropping with either no‐tillage or conventional. tillage for a period of 4 years did not significantly affect the soil productivity parameters measured in these soils, even though most of the above‐ground portion of the crops was harvested as silage. The results suggest that the productivity of high quality soils under similar intensive cropping systems probably could be maintained over a long period of time.

ISSN:0010-3624    

DOI:10.1080/00103628309367365

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Monthly recordings of NH+4‐N, NO−3‐N, redox potential, pH, and soil organic matter were made in soil profiles of four different commercial rice fields during the growing season. Ammonium was the prevalent form of mineral N until July, when an increase of NO−3‐N occurs. At the same time, there was a drop in redox potential and an increase in pH and soil organic matter content. These conditions are particularly favorable for N losses through denitrification. In September the relatively high concentrations of NO−3‐N indicate a possible leaching of nitrates after autumn rainfalls.

ISSN:0010-3624    

DOI:10.1080/00103628309367366

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

The chemical behaviour of iron chelates, incorporated in compound fertilizers with inorganic micronutrient compounds, was studied. Pot experiments were conducted to evaluate the effectiveness of these products in controlling iron deficiency. A commercial compound fertilizer, containing 0.09% Fe as Fe‐DTPA, 0.12% Cu, 0.16% Mn and 0.04% Zn as sulfates, proved to be ineffective in preventing iron chlorosis inChamaecyparis lawsoniana’Alumii’, growing on sphagnum peat at two lime levels. The same fertilizer formulation with 0.09%‐ Fe as Fe‐EDDHA did prevent iron chlorosis at both lime levels. Fe‐EDTA, incorporated in the compound fertilizer, gave good results at the lower but not at the higher lime level, due to the low stability of Fe‐EDTA at high pH. Data from laboratory experiments showed that copper replaced the chelated iron in the compound fertilizer containing Fe‐DTPA, causing the iron to precipitate. The strong competition between copper and iron for the organic ligand is due to a specific affinity of copper for DTPA, resulting in a copper chelate with high stability constant and a molar ratio of copper to chelating agent of 2 : 1.

ISSN:0010-3624    

DOI:10.1080/00103628309367367

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

Phosphorus applications ranging from 0 to 288 kg P/ha were broadcast alone and in combination with band treatments of 22 kg P/ha to two newlycleared Kempsville sandy loam (Typic Hapludults) soils for the purpose of measuring corn (Zea mays L.) yield responses and obtaining soil test calibration data. Four to 10‐fold corn grain yield increases resulted from P additions. Broadcast applications of 96 kg P/ha in combination with band treatments of 22 kg P/ha from either diammonium phosphate or ammonium polyphosphate were most efficient in increasing corn grain yields to 80% or more of maximum yield. Critical extractable soil P values for the two sites of 31 and 42, 29 and 37, 18 and 19, and 47 and 43 ppm were obtained for the Bray I, North Carolina (NC), Olsen, and Mehlich III soil test procedures, respectively. Increases in extractable soil P with increasing P applications expressed as ppm P/kg P applied varied for the two sites from 0.21 to 0.26 for the Bray I and NC procedures, 0.10 to 0.13 for the Olsen method, and 0.23 to 0.35 with the Mehlich III test.

ISSN:0010-3624    

DOI:10.1080/00103628309367368

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

摘要:

A computer program was written to determine particle size distribution and soil textural class by the U.S.D.A. system. The program, written in WATFIV, is based on the hydrometer method of particle size analysis.

ISSN:0010-3624    

DOI:10.1080/00103628309367369

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor

ISSN:0010-3624    

DOI:10.1080/00103628309367361

出版商:Taylor & Francis Group    

年代:1983

数据来源: Taylor