Illustrated Concepts in Tropical Agriculture, 1970 - 1981

Permanent URI for this collectionhttps://hdl.handle.net/10125/10697

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Green Manuring—Renewed Interest in an Old Concept
(University of Hawaii, 1981) Yost, R.S.; Evans, D.O.; Saidy, N.A.; Fox, R.L.
Three tropical green manure legumes were grown across a pH gradient from 4.7 to 7.1 established by liming an Oxisol. The effects of available soil aluminum and manganese levels on plant growth and nitrogen fixation are discussed.
Liming in the Tropics: Variable-Charge Soils May Be Highly Buffered
(University of Hawaii, 1981) Fox, R.L.; Saidy, N.A.; Yost, R.S.
Yield response of cowpea over a pH gradient established by applying incremental amounts of lime to an Oxisol is illustrated and discussed.
Mapping Soil Fertility and Fertilizer Requirements
(University of Hawaii, 1980) Fox, Robert L.; Yost, Russell S.
A map of fertilizer phosphorus requirements for the island of Hawaii is discussed. It shows the amount of P fertilizer required per gram of dry soil to establish 0.02 microgram P per milliliter of soil solution, a level that is capable of producing near-maximum yields of many agronomic crops.
Amorphous Coatings on Soil Mineral Surfaces Sorb Phosphate and Sulfate
(University of Hawaii, 1978) Jones, Rollin C.; Fox, Robert L.
Soils formed in weathered volcanic ash usually contain a high percentage of amorphous gel-like material that has been desilicated during weathering. The influence of this property on phosphate and sulfate sorption is discussed.
The External Phosphorus Requirements of Plants
(University of Hawaii, 1980) Fox, Robert L.; Nishimoto, Roy K.
The dynamic between labile P, soil solution P, and P uptake by lettuce and Chinese cabbage is illustrated.
Symbiotic Nitrogen Fixation by Legumes Requires Extra Phosphorus
(University of Hawaii, 1980) Cassman, Kenneth; Whitney, A Sheldon; Fox, Robert L.
Soybean plants that depend upon symbiotic nitrogen fixation for their N have a higher P requirement than their counterparts supplied with fixed N from an external source.
Premature Leaf Senescence of Banana—A Symptom of Potassium Exhaustion
(University of Hawaii, 1980) Fox, Robert L.; Lower, Robert
Tropical soils may lack reserves of available K due to nutrient leaching, and harvesting of K-rich crops such as banana may deplete the limited reserves. Symptoms of gradually increasing K deficiency over a 6-year period are illustrated and described.
Nitrogen and Potassium Interact to Shape a Yield Response Surface
(University of Hawaii, 1980) Fox, Robert L.; Lower, Robert; Warner, Robert M.
In a field experiment with banana, fertilizer variables were applied systematically in strips across the blocks so that N increased gradually from none to large quantities in one direction, while K increased gradually perpendicular to the N fertilizer. An aerial view of the blocks and a plot of banana yields as influenced by the variables illustrate the interaction of the nutrients applied.
Matching Crop Requirements to Land Characteristics
(University of Hawaii, 1980) Manrique, Luis A.; Harris, David J.; Uehara, Goro
Examples of matching crop, soil, and season are given; implications for technology transfer in the tropics are mentioned.
Mycorrhizae Enhance Nutrient Uptake from Infertile Soils
(University of Hawaii, 1980) Yost, Russell S.; Fox, Robert L.
A field experiment to illustrate how removing soil mycorrhizae through fumigation affects the growth of crops dependent on the symbiosis is discussed.
Water and Salts Move Together in the Soil Profile
(University of Hawaii, 1980) Fox, Robert L.; Green, Richard E.
Soil water movement dynamics relative to soil properties is briefly outlined, and its relationship to movement of salts is discussed.
Soil Properties and Root Distribution Determine Water Availability to Crops
(University of Hawaii, 1978) Green, Richard E.; Fox, Robert L.
The importance of depth of rooting during seasonal droughts is illustrated, and the facts that influence rooting depth are discussed.
Nitrogen Application Promotes Root Proliferation and Vegetative Growth of Corn
(University of Hawaii, 1977) Asghar, M.; Kanehiro, Y.
The effect of urea nitrogen fertilizer on corn root and shoot growth is illustrated.
Symptoms of Plant Malnutrition--Visual Symptoms and Incipient Malnutrition
(University of Hawaii, 1972) Fox, Robert L.
Corn was grown across a gradient created with increasing doses of urea fertilizer. Comparison of a photograph of the corn row with a plot of the yield of fresh husk sweet corn revealed that disappearance of visual N deficiency occurred well before maximum yield was reached. This illustrates the need for more sophisticated means of determining optimal fertilizer levels than can be obtained by mere visual observation, which fails to detect "hidden hunger" in plants.
Low Soil Temperatures Depress Root Activity in the Tropics
(University of Hawaii, 1973) Ravoof, A.A.; Fox, R.L.; Sanford, W.G.
In summer, the humid tropics are more temperate than much of the temperate zone. Growth and uptake of N, P, and K by pineapple did not increase at root-zone temperatures above 25C and were inhibited by temperatures below that. Use of black plastic mulch was shown as an example of how pineapple crop soil temperature can be favorably affected.
Residual Efficiency of Fertilizer Phosphorus: Field Evaluation
(University of Hawaii, 1978) Fox, Robert L.; Plucknett, Donald L.
The fate of various levels of phosphorus applied to a grass-legume forage mixture on a strongly P-"fixing" Gibbsihumox soil was tracked over 9 years. The status of the plots at the end of that time is shown in a photo, and the forage yield in the plots is plotted against P applied for four occasions of sampling over the period.
Liming in the Tropics: Comparative Response of Tropical and Temperate Legumes
(University of Hawaii, 1978) Fox, Robert L.; Munns, Donald N.
Few legumes grow well when manganese or aluminum dominate the suite of exchangeable cations, as they do in certain acidic soils of Hawaii. An Oxisol was given increasing amounts of agricultural lime such that a soil pH gradient from 4.8 to 7.1 was established. The differing growth responses of leucaena, alfalfa, and stylo are shown.
Symptoms of Plant Malnutrition--Silicon, an Agronomically Essential Nutrient for Sugarcane
(University of Hawaii, 1978) Fox, Robert L.; Silva, James A.
Deficiences of silicon in a Si-deficient soil (a Gibbsihumox) causing a "leaf freckle" disorder are illustrated with photos of sugarcane leaves from plants grown with or without an application of calcium silicate slag. Effects of diminished leaf growth caused by silicon deficiency on presence of weeds under the canopy are also shown.
Crop Quality Control Through Soil Management Techniques: Manipulating Nitrogen and Water to Ripen Sugarcane
(University of Hawaii, 1973) Fox, Robert L.; Isobe, Minoru
Controls to reduce available nitrogen and soil water in a maturing sugarcane crop can have a positive influence on the yield and quality of the cane.
Improved Stiff-strawed Rice Varieties Utilize Nitrogen More Effectively Than Traditional Varieties
(University of Hawaii, 1978) Fox, Robert L.; Rotar, Peter P.
Traditional Indica rice varieties offered little chance of yield response to increased nitrogen fertilizer because they were prone to lodging (bending over) when they grew too tall. Development of dwarf rice cultivars with stiffer stems enabled rice farmers to increase yields with N inputs. Photos compare the tall and dwarf types and illustrate lodging.

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