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Zinc sulfate (ZnSO4 · H2O) has traditionally been the “reliable” source of zinc (Zn) fertilizer, but other sources of Zn are also available. Some are derived from industrial by‐products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn mobility in Zn sources derived from these various by‐products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this column study was to compare the mobility of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. The sources included three granular inorganic Zn sources, two granular organically complexed Zn sources, and liquid ZnEDTA. Soil columns were leached five times with deionize...

Micronutrient deficiencies in plants are common throughout the world. Many inorganic and organic fertilizers are manufactured and applied to soils and plants to correct micronutrient deficiencies. The objective of this article is to review current research and present our findings on factors that affect micronutrient fertilizer efficacy. In the United States, state laws regulate the “guarantee analysis” of fertilizers and essentially all states require that manufacturers meet a total analysis requirement. However, there is no consideration of micronutrient “availability” in this analysis. Our research has shown that Zn availability in granular fertilizer was related to water solubility (r2=0.92) and not total Zn content. The relative availability coefficients for organic and inorganic Zn fertilizers was also highly related to water solubility and independent of total Zn content. Because of this discrepancy, there are fertilizers in the marketplace that are very low in plant available micronutrien...

Zinc sulfate (ZnSO4) has traditionally been the “reliable” source of Zn fertilizer but other sources of Zn are also available. Some are derived from industrial by-products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn availability in Zn sources derived from these various by-products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this greenhouse study was to determine the availability coefficients of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. We evaluated the dry matter production, total Zn uptake, and Zn concentration in corn (Zea mays L. cv. P3752) plants fertilized with six different commercial Zn fertilize...

Coal fly ash has physical and chemical characteristics that makeit useful as a soil amendment, one of the more important beingthe potential to permanently improve the soil water relations ofsandy, drought-prone soils. We axemined changes in theinfiltration rate and water holding capacity of a sandy soilafter application of high rates (up to 950 Mg ha-1) of aClass F fly ash. Fly ash was applied to large field plots byeither conventional tillage (CT; moldboard plow-disk) orintensive tillage (IT; chisel plow-rotovate-disk), and tomicroplots using a rototiller. Infiltration rate (i) wasmeasured in both studies with a disk permeameter on threeoccasions over a 12-month period. Ash effects on gravimetric water content (θg) at the 0–40 cm soil depth were measuredduring a 168 hr period following a 2.5 cm rainfall event andwater release curves (33 to 500 kPa) were constructed in thelaboratory using soils from the large plots. In both studiesi was decreased by ∼80% one year after additionof fly ash and θgin ash-amended soil was higher than unamended soil throughoutthe 168 hr monitoring period. Soil water distribution variedwith tillage; the IT treatment had the highest θg increasesin the 0–20 cm depth while the CT treatment had θgincreases throughout the 0–40 cm depth. Soil water content anddistribution in ash-amended microplots were similar to ITtreatments. Fly ash amendment not only increased water holdingcapacity but also increased plant available water by 7–13% inthe 100–300 kPa range. These results suggest fly ash amendmentmay have the potential to improve crop production in excessivelydrained soils by decreasing i and increasing the amountof plant available water in the root zone.

Alternatives to landfilling fly ash may be to use it as a soil amendment since it is fine textured and could alter soil texture and thus improve water retention. However, fly ash contains elevated B, soluble salts, and trace element concentrations that could adversely affect plant and soil quality. Objectives were to characterize leaching of soluble salts, plant nutrients, and trace elements in a sandy soil amended with a high rate of fly ash ({approximately}662 Mg ha{sup -1}). We established Field plots in an Evesboro loamy sand using typical agricultural equipment. Lysimeters were installed to a depth of 120 cm and used to collect leachate over a 9 mo period. We also used microplots; (1.0 by 1.0 m) and similar ash rates to characterize leaching under controlled conditions. Lysimeters were installed at four depths in each microplot (15, 30, 60, and 120 cm) and water applied with a rainfall simulator. Boron and soluble salts were leached from the rooting zone after {approximately}38 cm of natural rainfall or 42 cm of irrigation. Calcium and S were the dominant plant macronutrients in leachates while Cu, Mn, and Zn were the only detectable micronutrients. Peak concentrations of these elements were detected after {approximately}50more » cm of rainfall or irrigation and decreased to below or near initial concentrations by the conclusion of the study. Nickel was the only detectable trace element in leachates, however, concentrations were variable and

Characteristics of a well–established population of the mantid, Tenodera sinensis (Saussure), were examined during the adult portion of its life cycle, for three consecutive years (1990–1992). During the fall of 1992, changes in body mass of females in well-fed and starved experimental cohorts were compared with those in the open field, as a measure of food limitation in this population. The open field cohort maintained mean body mass at a level intermediate to the experimental cohorts. However, some individuals in the field did as well as those in the well–fed cohort, whereas none did as poorly as in the starved cohort. Ootheca production was greatly reduced in 1992 compared with the previous 2 yr. This could not be attributed to food limitation, because even well–fed experimental animals failed to oviposit. Lower temperatures in 1992 slowed development rate, reducing the number of females that reached imago in time to oviposit before killing frost. Thus, even when food limitation is not severe, stochastic reduction in degree–days could cause local or even regional extinction, especially in temperate univoltine species of low vagility such as T. sinensis .

Many approaches have been proposed over the last two decades for managing the spatial variation of soil and crops. In this chapter we discuss the importance of quantifying and managing spatial variation in crop production fields to implement site-specific crop management. We outline the challenges that soil and crop scientists have addressed since the inception of precision agriculture (PA) in terms of managing soil spatial variation, and the development of simple, stable and inexpensive techniques for quantifying and managing it with tools such as site-specific management zones. This chapter summarizes and cites the work of several scientists who have worked in the area of development and evaluation of site-specific management zones from around the world. Geostatistics is being applied increasingly in PA because of the need for accurate maps on which to base site-specific management. For soil and crop properties that require costly sampling and analysis, there are often insufficient data for geostatistical analyses and this chapter shows how management zones can provide an interim solution to more comprehensive site-specific management. Physical and chemical soil properties have been the most widely used properties for delineating management zones, however, intensive data from remote and proximal sensors are being used increasingly. The case study describes methods of delineating and evaluating management zones.