摘要:

Several authors have observed that the availability of soil potassium (K) is affected by environmental and soil factors,e.g.moisture content although the extent of the effect is still uncertain. In a pot experiment carried out with corn(Zea maysL.) for five weeks, effects of two K dosses at two soil moisture levels were studied on the K uptake of young plants. Soils were collected from plots of long‐term fertilization trials representing different K levels. Results of the experiment show that amounts of K taken up by the plants were greatly dependent on soil moisture and available K levels. Soil moisture did not affect the very close linear relationship between dry matter production and K uptake of young corn plants.

ISSN:0010-3624    

DOI:10.1080/00103629409369147

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The objective of this study was to determine the soil conditions that affect growth and yield of citrus orchards growing under a semiarid climate in Northwestern Mexico. Separate soil samples of High‐ and Low‐yielding areas in growth and yield were taken on seven orchards. In each area, yield, salinity, pH, infiltration velocity (Iv), and soil compaction were determined. The average yield in the High‐yielding areas was 162 kg/tree and in the Low‐yielding areas 48 kg/tree. The soil compaction was 15 bars higher in the Low‐yielding areas as compared to the High‐yielding areas. Regarding soil analyses, the average values in the Low‐yielding areas were: ECe = 3.8 dS/m, sodium = 17 meq/L, calcium = 16 meq/L, magnesium = 3.8 meq/L, and exchangeable dodium percent (ESP) = 7.2. On the other hand, the average values for the High‐yielding areas were: ECe = 1.1 dS/m, sodium = 6 meq/L, calcium = 4 meq/L, magnesium =1.2 meq/L, and ESP = 4.6. In the Low‐yielding areas, a 10 cm water table can be infiltrated in 11 days, while in the High‐yielding areas, this infiltration occurs in a few hours.

ISSN:0010-3624    

DOI:10.1080/00103629409369148

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The acid ammonium acetate‐EDTA universal extractant developed at Agricultural Research Centre of Finland is introduced. The method has already been globally used in soil testing and pollution studies. The introduced correction factors based on soil general properties improve the interpretation of analytical data obtained. The method has proven to be useful in testing non alkaline soils. The development of interpretation for more elements increases the usefulness of the method further.

ISSN:0010-3624    

DOI:10.1080/00103629409369149

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Research was conducted during two growing seasons to determine nitrogen (N) and sulfur (S) fertilizer recovery of Coastal bermudagrass [Cynodon dactylon(L.) Pers.] on a S‐deficient Rilla silt loam (Fine‐silty, mixed, thermic Typic Hapludalf) soil in the Gulf Coastal Plain of the southeastern United States. Sulfur was applied as gypsum or wettable S at the annual initiation of forage growth at 100 kg S/ha. Nitrogen was applied as ammonium nitrate (NH4NO3), urea, and 32% urea‐ammonium nitrate (UAN) solution at rates of 0, 224, and 448 kg N/ha in four split applications. Nitrogen sources did not significantly influence N or S recovery. However, both N and S sources did significantly interact with N rates to affect N and S recovery. Nitrogen recovery declined with increasing N rates but was significantly higher when coupled with S fertilizer. Sulfur recovery increased with increasing N rates with higher recoveries for gypsum than for wettable S.

ISSN:0010-3624    

DOI:10.1080/00103629409369150

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Soil analytical results arc presented based on long‐term field experiments conducted by the Hungarian Academy of Sciences, Research Institute of Soil Science and Agrochemistry. Owing to the long‐term fertilizer and/or manure applications, there are significant differences in the amounts of soluble organic nitrogen (N) fractions and also in the 0.01 M calcium chloride (CaCl2)‐soluble phosphorus (P) and potassium (K) contents. The P and K balances in the different treatments and the 0.01M CaCl2‐soluble P and K content of the soil highly correlate.

ISSN:0010-3624    

DOI:10.1080/00103629409369151

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The 0.02M strontium chloride (SrCl2) and 0.05M citric acid solution (Sr‐citrate) was developed for the simultaneous determination of availability indices for plant nutrients from soils. The objective of this study was to compare the Sr‐citrate extracting solution with water, 0.002M SrCl2, 0.1M barium chloride (BaCl2), 0.1M hydrochloric acid (HCl), 1M ammonium acetate (NH4OAc), and Mehlich 3 soil extractants as predictors of plant‐available potassium (K) for alfalfa(Medicago sativaL.) in the greenhouse. The Sr‐citrate solution extracted more soil K than SrCl2and BaCl2but less than the other extractants. The Sr‐citrate solution was best for predicting K uptake from low cation exchange capacity (CEC < 15 cmolc/kg) soils and adequately predicted plant uptake from higher CEC soils and the relative yield of alfalfa in all soils. The relationship between Sr‐citrate K and plant uptake was slightly improved when boiling nitric acid (HNO3)‐extracted K or organic matter content was included in the multiple regression equation. The results of this study show that the Sr‐citrate procedure can adequately predict the amount of plant‐available K in soils.

ISSN:0010-3624    

DOI:10.1080/00103629409369152

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Nitrogen (N) fertilizers used in corn production contribute to the occurrence of nitrate to ground water. Tissue testing is a tool that can aid in fertilizer N management. Several tissue testing techniques were evaluated for their potential to aid in N management of irrigated corn in Nebraska. Leaf N content provided a traditional means of identifying N deficiencies in corn. Leaf N concentrations were difficult to interpret because of luxury consumption and the lack of consistent critical levels across hybrids and growth stages. Chlorophyll meters showed little sensitivity to luxury consumption and provided instantaneous results, but required an in‐field reference fertilized with extra N. Chlorophyll meter readings were highly correlated with grain yield and provided early detection of a N deficiency. The combination of chlorophyll meter data and irrigation demonstrated the merits of a “fertilization‐as‐needed”; approach to N management. The post‐harvest stalk nitrate test accurately identified situations with excess N available to the corn crop. This test does not require an in‐field reference to evaluate N management after the fact, and also indicates environmental implications of N fertilizer practices.

ISSN:0010-3624    

DOI:10.1080/00103629409369153

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

In Eastern Canada, barley yields are often restricted by soil acidity and low fertility as well as by structural degradation. The addition of lime and fertilizers and reduced tillage are proposed practices which may have a large impact on soil reaction and nutrient extractability. The objective of this work was to assess the impact of three years of differential tillage intensity (minimum, MT; chisel plow, CP; and moldboard plow, MP) and of lime and P additions on pH and Mehlich‐3 extractable nutrients in the 0–7.5, 7.5–15, 15–30, and 30–45 cm soil layers of a Courval clay loam (fine, mixed, frigid, Aeric Humaquept). This study has shown that lime reaction was limited to the depth of incorporation in this clay soil. Lime, when added at moderate amounts, resulted in significant increases in soil phosphorus (P) extractability under all tillage intensities and reductions in extractabile zinc (Zn) and manganese (Mn), whereas potassium (K) and magnesium (Mg) were not significantly affected. Subsoil‐extractable Mg was brought closer to the surface in the plow treatments. The use of the chisel plow as primary tillage has resulted in increased soil P, K, and Mn extractabilities. Extractable Zn was larger under moldboard plowing. It is possible that, because of a better distribution of plant residues, larger microbial biomass activity under CP is responsible for these observations. Chisel plow is a good alternative to moldboard plowing in this soil as it incorporated lime and plant residues more evenly while reducing fixation of added fertilizers.

ISSN:0010-3624    

DOI:10.1080/00103629409369154

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Cassava(Manihot spp)and green (unripe) plantain(Musa spp.,AAB group) peels are a cheap source of feed to ruminant livestock in Ghana. Since cassava and plantain availability in large quantity is seasonal, effective utilization of the peels can be obtained by sun‐drying (processing) to increase its dry matter content and enhance its storability. A study was conducted to determine the effect of sun‐drying on the chemical components of the peels with the view to enhance peel utilization by small scale ruminant livestock farmers in Ghana. The colour and texture of the peels changed appreciably after processing. The observed peel to pulp ratios (wet basis) were 53:47, 40:60, and 21:79; and 36:64, 27:73 and 15:85 (dry matter basis) for French‐, and False‐horn plantains and cassava, respectivley. Significant increases in dry matter content (15.14% to 94.00%, 17.51% to 91.00% and 30.02 to 87.64%) for French‐, False‐horn plantain and cassava peels, respectively, resulted from the processing (P<0.05). Sun‐drying increased the acid detergent fibre (ADF), acid detergent lignin (ADL), and acid detergent insoluble nitrogen (ADIN). But decreased substantially reducing sugar, chlorine, and iodine concentrations (non significant, P>0.05) in the sun‐dried peels. The treatment does not seem to influence the quality of feed in terms of energy and digestible organic matter.

ISSN:0010-3624    

DOI:10.1080/00103629409369155

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Xylem sap extraction from decapitated plants by negative pressure will be discussed in this paper. This method of extraction, in which transpiration is simulated by a negative pressure, uses as a quantitative reference generated by non‐decapitated plants. For this method, several horticultural plant have been used with the main nutritive elements in the sap analyzed by ionic chromatography.

ISSN:0010-3624    

DOI:10.1080/00103629409369156

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor