Jerry B. Sartain

Land Application of Aluminum Water Treatment Residual: Aluminum Phytoavailability and Forage Yield

Negative impacts of land‐applied aluminum (Al)–rich water treatment residuals (WTRs), which have been suggested to improve soil phosphorus (P) sorption, could include excessive immobilization of plant‐available P and Al phytotoxicity. We studied the impacts of an Al‐rich WTRs on agronomic returns and plant Al concentrations in glasshouse and field studies. The glasshouse study was a 4 × 2 × 3 factorial experiment with one control in a randomized complete block design and three replicates. Four sources of P were each applied at two agronomic rate [44 kg P ha−1, P‐based rate; and 179 kg plant‐available nitrogen (PAN) ha−1, N‐based rate] to topsoil (0–15 cm) of a sandy, siliceous, hyperthermic Arenic Alaquods. Three WTR rates (0, 10, and 25 g kg−1 oven‐dry‐weight basis) were further applied, whereas the control received neither P source nor WTRs. Bahiagrass (Paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were continuously grown in succession for 18 months. Applied WTRs increased soil Al but not plant Al concentrations (22–80 mg Al kg−1), which fell within the normal concentration range for pasture plants. In the glasshouse, when WTRs were incorporated with the soil, bahiagrass dry matter (DM) accumulation was reduced, but ryegrass DM was not affected even at 25 g kg−1 WTR. A 2‐year field study, with same treatments but two rates of WTRs (0 and 10 g kg−1 WTR) surface applied to established bahiagrass on the same soil type (Spodosols) showed neither reduced yields nor increased plant Al phytoavailability in the WTR treatments. The studies show no increase in plant Al is associated with Al‐WTRs applied to reduce excess soil‐soluble P and P losses but plant DM accumulation may be reduced.

Water movement through an aggregated, gravelly oxisol from cameroon

Abstract Increasing population pressures have caused increased utilization of the gravelly (stone line) soils common to the hilly landscapes of equatorial Africa. This study was conducted to determine if macropore water flow and immobile-water regions should be considered in describing solute movement while developing nutrient-management strategies. Break-through curves (BTCs) from miscible displacement experiments with tritiated water were measured from 70-cm long by 9.6 cm internal diameter, water-saturated, undisturbed soil columns. Simulations produced by theoretical transport models were fitted to the BTCs to determine the magnitude of dispersivity and immobile-water regions. Gravel separates composed of kaolinite, gibbsite, goethite and manganese oxides had porosities ranging from 0.13 to 0.32 m 3 /m 3 , with a composite sample porosity of 0.20 m 3 /m 3 . Adsorption coefficients of tritium ranged from 0.031 to 0.052 ml/g for the three horizons in the soil columns. Columns containing gravel (30% by volume and 62% by weight) gave asymmetrical BTCs. A convective-dispersioe (CD) transport model was unable to simulate observed BTCs accurately. The mobile/immobile (MIM) water model provided close agreement to BTCs obtained at flow rates ranging from 2.71 to 111 cm/d. The water-saturated soil columns had about 50% of all water in immobile regions. Soil water dispersivity was 3.3 cm 2− n d n −1 (with empirical constant n =1.3) from a curvilinear plot of the dispersion coefficient and the mobile pore-water velocity. Parameters estimated from one column were applied to the BTCs of a similar soil column. The MIM model showed close agreement between the measured and the independently estimated BTCs. These soil characteristics can contribute to the rapid deep transport of a limited quantity of solute and to the storage and/or slow diffusive mass transport of the remaining solute from within immobile regions.

Fertilizer effectiveness of three carbonate apatites on an acid ultisol

Abstract Two properties that are detrimental to agronomic production with acid tropical soils are elevated aluminum concentrations and low phosphate availability. Direct application of carbonate apatites to acid tropical soils possessing low buffering capacity could possibly resolve this problem. The property that determines the effectiveness of directly‐applied carbonate apatites is the CO3/PO4ratio, which indicates the degree of anionic isomorphic substitution occurring within the mineral crystal lattice. Increasing ratios denote greater mineral solubility under acid‐soil conditions. Research was conducted to determine: a) fertilizer efficiency of three carbonate apatites (from North Carolina (NCPR), Central Florida (CFPR), and Kodjari, Upper Volta (KPR)), varying in CO3/PO4ratios, to that of triple superphosphate (TSP), and b) liming effects induced by the liberation of carbonates from each source, compared to CaCO3. Maize (Zea mays L.) was grown in pots containing 3 kg of a Dothan fine sandy loam (fin...

Yield response of soybeans to P and K fertilization as correlated with soil extractable and tissue nutritional levels 1

Abstract Bragg soybeans [Glycine max. (L. ) Merill] were grown under field conditions near Sanford, Florida on a tile‐drained Immokalee fine sand (sandy, siliceous, hyperthermic Arenic Haplaquod). The objectives were: 1) to assess the K and P fertilizer requirements of soybeans grown in central Florida 2) to correlate soil and tissue nutritional levels with extractable soil nutrients and 3) to assess the influence of K application time on yield. Experimental treatments were four K rates (0, 50, 100, and 200 kg K/ha), three P rates (0, 25, and 50 kg P/ha), and two sidedress K rates (0 and 50 kg K/ha) at early bloom. Treatments were arranged in a randomized complete block design and replicated four times. Yield increased with each increase in applied K. Statistical maximum yield was obtained on plots which contained 103 ppm double‐acid extractable K during the pod‐filling stage of growth. Tissue K at early bloom exceeded 2.85% at maximum statistical yield. Potassium applied broadcast at early bloom did not ...

Relative Phosphorus Phytoavailability of Different Phosphorus Sources

Understanding differences in the phytoavailability of various phosphorus (P) sources should improve matching P additions to plant needs and minimize excessive buildup of bioavailable P, which can degrade aquatic systems. We evaluated relative P phytoavailability (RPP) of different P sources in glasshouse and field studies. Bahiagrass (Paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were grown in succession in a P‐deficient soil amended with four sources of P (triple superphosphate (TSP), Boca Raton and Pompano; biosolids, and poultry manure), each applied at two rates in the glasshouse study and to an established bahiagrass pasture in the field. The RPP values estimated from plant P uptake of each organic source of P relative to TSP in the glasshouse were similar for the three croppings and similar to the estimates derived from the field study, but varied for the different P sources. Values ranged from 30% for poultry manure to 85% for Boca Raton biosolids. Boca Raton biosolid P was as readily available as P in TSP and would be classified as a high RPP (>75% RPP) source, but Pompano biosolids and manure would be classified as moderate RPP materials (25–75% RPP). The RPP values observed in manure and Pompano biosolid treatments are consistent with 50% “effectiveness” suggested for biosolid P in U.S. Environmental Protection Agency (USEPA) guidelines, whereas P bioavailability of Boca Raton biosolids is similar to mineral fertilizer.

Chemical characteristics and microbial degradation of humate

Abstract Humates are often used in agriculture as a source of organic matter. This study was conducted to characterize a commercial humate and to evaluate its chemical and decomposition characteristics. Characterization methods included fractionization of humic and fulvic acids of the humate, based on their alkali/acid insolubility; elemental analysis; acidic functional group analysis; and E4/E6 ratio determinations. The humate consisted of the following: 58% organic matter, 32% ash, and 10% moisture. Humic fraction was mostly humic acid (76%), with some fulvic acid (18%). Organic elemental composition [59% carbon (C), 5% hydrogen (H), and 36% oxygen (O)] also suggests a humic‐acid nature. Inorganic elemental content of this humate, which was primarily aluminum (Al) [4.9%] and iron (Fe) [0.46%], reflects its spodic origin. Much of the Al present, however, results from the flocculant (alum) used at the mining site to precipitate the humate. The relatively low total acidity of this humate (250 cmol/kg) sugg...

NITRATE LEACHING AND TURF QUALITY IN NEWLY SODDED ST. AUGUSTINEGRASS

There are increasing concerns about the fate of fertilizers applied to lawn grasses. The objectives of this research were to evaluate nitrate leaching and turf response to nitrogen (N) treatment and irrigation in newly sodded St. Augustinegrass. The research was conducted in Citra, FL in 2006 and 2007. Nitrogen was applied at three rates day of sodding and again at 30 days after planting. Analysis of variance indicated there were no differences in nitrate-N (NO3–N) leached due to N treatment or timing. During the establishment period, NO3–N loading was greater than reported for established turf and could possibly present a source of nitrate contamination. Turf quality and color were above or just below an acceptable score at all N rates. Due to the potential for high amounts of NO3–N leaching in new sod, it is not recommended to apply N fertilizer to St. Augustinegrass in the first 30–60 days after planting.

Comparison of Soil P Test Procedures for St. Augustinegrass

St. Augustinegrass [Stenotaphrum secondatum (Walt.) Kuntze] is a home lawn grass widely used in the southern United States. At present, phosphorus (P) fertilization of St. Augustinegrass is based primarily on Mehlich 1 P test. One criticism of Mehlich 1 extractant is that it extracts some fraction of soil P pool that is not available to plants, whereas, iron (Fe) oxide P and water‐extractable P methods are reported to be better related to plant growth in some cases. Literature relative to the soil test procedure comparison for St. Augustinegrass was not found. The objective of this study was to evaluate Mehlich 1 P, Fe oxide P, and water‐extractable P to identify the most suitable soil test method for St. Augustinegrass growth. Established pots of ‘Floratam’ were subjected to P application of 0, 0.14, 0.27, 0.54, and 1.07 g m−2 every 4 wk for 12 wk. Measurements included tissue growth rates, tissue P concentration, soil Mehlich 1 P, Fe oxide P, and water‐extractable P concentrations. Phosphorus application increased soil test P concentrations. Soil Mehlich 1 P, Fe oxide P, and water‐extractable P concentrations were closely correlated to each other. Three soil test P levels and tissue P concentrations were highly correlated with Mehlich 1 P, which best predicted tissue P levels. Three soil test P levels were also closely correlated to the St. Augustinegrass top growth rate. Critical minimum Fe oxide P and water‐extractable P concentration was 3 mg kg−1. Overall, Mehlich 1 P was the best soil P test for St. Augustinegrass among the three extractants tested.

Soil‐Test Methods for Florida Sands Treated with an Aluminum–Water Treatment Residual and Various Phosphorus Sources

Use of aluminum (Al)–rich water treatment residuals (Al‐WTR) has been suggested as a practice to immobilize excessive phosphorus (P) in Florida soils that could represent an environmental hazard. Fertilizer P requirements can differ in WTR‐amended and unamended soil, so careful selection of soil‐testing methodology is necessary. Acidic extractants can dissolve WTR sorbed P and overestimate plant‐available P. We evaluated the suitability of the Mehlich 1 P (M‐1P) and other agronomic soil‐test procedures in an Al‐WTR‐treated Florida soil. Bahiagrass (paspalum notatum Fluggae), ryegrass (Lolium perenne L.), and a second bahiagrass crop were grown in succession in a Florida topsoil amended with four sources of P at 44 kg P ha−1 (P‐based rates) and 179 kg PAN ha−1 [nitrogen (N)–based rates] and three WTR rates (0, 10, and 25 g kg−1 oven‐dry basis). Both water‐extractable P (WEP) and iron (Fe) strip P (ISP), but not M‐1P, values of soil sampled at planting of each grass were greater in the absence than in the presence of WTR. Total plant P uptake correlated with WEP (r2 = 0.82***) and ISP (r2 = 0.75***), but not M‐1P (r2 = 0.34***). Correlations of the dry‐matter yield, P concentration, and P uptake of the first bahiagrass were also better with WEP and ISP than with M‐1P values. However, regression of plant responses with M‐1P improved after the first crop of bahiagrass. Both WEP and ISP values were better predictors of available soil P than M‐1P in a field study with same four P sources surface applied to established bahiagrass at the same two P rates, with and without WTR. Both WEP and ISP are recommended as predictors of P adequacy in soils treated with WTR, especially for soils recently (< 5 months) treated with Al‐WTR.

Effects of residual and applied κ on soybean nodulation, root growth, pod formation and K and N composition

Abstract Inoculated soybeans (Glycine max L. Merr. cv. Eragg) were grown in an intensively managed cabbage (Brassica oleracea L. Capitata group)‐ sweetcorn (Zea mays L.) multiple‐cropping sequence on a tile‐drained Arenic Haplaquod having variable residual K levels. The study was conducted to assess the effect of residual and applied K on soybean K and N composition, nodulation, root growth, and pod formation. Sidedress treatments of 0 and 100 kg K/ha were applied at bloom to plots that received either 0 or 300 kg K/ha/acre that had been applied previously to other crops in the sequence. Treatments were arranged in a randomized complete block design witn six replications. Although leaf N conc, was uniform at bloom (R2), leaf N at pod‐fill (R6) ranged from 2.8 to 4.3% and wasquadratically related to leaf K (r2 = 0.92). Without residual K fertilizer from cabbage and sweet corn applications sidedress application of K increased leaf and nodule K and N. Root K conc. was correlated with root dry wt. (r = 0.35) ...