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Drought resistance of putting green cultivars is receiving increased attention due to irrigation restrictions. Potassium, which reduces turfgrass tolerance to environmental stresses when deficient, is often applied at rates equal to or greater than N in an attempt to increase its efficacy. Drought resistance for recently established ‘TifDwarf’ (TD) and ‘TifEagle’ (TE) bermudagrasses [Cynodon dactylon(L.) Pers. × C. transvaalensisBurt Davy], ‘SeaDwarf’ (SD) seashore paspalum (Paspalum vaginatumSwartz), and ‘PristineFlora’ (PF) zoysiagrass [Zoysia japonicaStued. by Zoysia tenuifolia(L.) Merr.] was evaluated under varied irrigation and K levels on a U.S. Golf Association (USGA)‐specified research green. Irrigation treatments were applied in the spring and fall of 2009 and spring 2010, and included 25, 50, and 100% of potential evapotranspiration (ETo), as calculated using the Blaney–Criddle equation. Nitrogen at 4.9 g m−230 d−1and K (as KCl) in 1N:1K, 1N:2K, 1N:3K, and 1N:4K fertilization ratios were applied at the beginning of each experiment. All cultivars had objectionable wilting (>10%) at 25% ETo in 2009, although PF and SD had least in the fall. In 2010 PF and SD did not exhibit objectionable wilting at any irrigation level. At 50% ETo, TD and TE wilted objectionably in all experiments, as did PF in the fall of 2009. In 2010, the bermudagrasses exhibited objectionable wilting under daily irrigation at 100% ETo. Increasing K in relation to N failed to increase drought resistance for the cultivars studied. The bermudagrasses had the least drought resistance and PF and SD the most.

Municipal biosolids (MBS) represents an alternative source of nutrients for the production of bioenergy crops like elephantgrass (Pennisetum purpureumSchum.). Two experiments were conducted during 2 yr in Florida to evaluate the effect of soil incorporation vs. surface application of MBS on: (i) elephantgrass dry matter (DM) yield, tissue N and P concentration and removal, and soil C and P (Exp. 1); and (ii) organic N mineralization and DM decomposition rates of MBS measured in the field using a litter bag incubation technique (Exp. 2). In Exp. 1, three treatments supplied 350 kg total N ha−1yr−1from surface‐applied municipal biosolids (MBS‐SA), soil‐incorporated municipal biosolids (MBS‐INC), and surface‐applied ammonium nitrate (NH4NO3). A fourth treatment provided 700 kg total N ha−1yr−1from MBS‐SA (double rate of municipal biosolids, 2x‐MBS). In Exp. 2, MBS was field incubated in litter bags placed on the soil surface or at a 5‐cm soil depth. Elephantgrass DM yield, and N and P removal were greater for MBS‐INC than MBS‐SA. Dry matter yield for MBS‐INC was not different than for NH4NO3fertilizer (22.5 vs. 24.3 Mg ha−1). Removal of N and P increased 39 and 10 kg ha−1yr−1, respectively, for MBS‐INC and MBS‐SA. Total organic N mineralized was greater for MBS‐INC (386 g kg−1) than MBS‐SA (308 g kg−1). Incorporation of MBS increases elephantgrass DM yield and nutrient removal compared to surface application and allows MBS to replace a greater proportion of inorganic N fertilizer.

In Florida, state agencies are concerned about St. Augustinegrass [Stenotaphrum secundatum(Walt.) Kuntze] for being a possible high water user and excess (N) applications in home lawns. This has resulted in a desire by some municipalities to substitute St. Augustinegrass with bahiagrass (Paspalum notatumFlügge). Consequently, the aim of this study was to determine the effect of different N fertilizer rates on water use and turf quality of bahiagrass and St. Augustinegrass commonly used in residential yards. The experiment was a split‐plot randomized complete block design repeated over two trials. Whole plots arranged in blocks consisted of either bahiagrass cultivar ‘Pensacola’ or St. Augustinegrass cultivar ‘Floratam’. Subplots consisted of two N rates (98 and 294 N kg ha−1yr−1). Water use rates, was influenced by grass type and by N rates with bahiagrass having higher water use rates (WURs) than St. Augustinegrass in one of the two trails. The high N rate increased turfgrass WURs but only in Trial 1. In both trials clipping yields (CY) were greater for bahiagrass than St. Augustinegrass. Furthermore, the higher N rate produced greater CY than the lower N rate. All treatments produced acceptable turfgrass quality when averaged for each trial though, not for ever cycle. Bahiagrass generally produced superior quality ratings than St. Augustinegrass. In addition, the higher N rate always produced higher quality scores than the lower N rate.

Proper fertilization of golf course putting greens during grow‐in provides rapid turfgrass cover, high quality putting surfaces, and limits environmental impacts. Different levels of N and K were applied to ‘TifDwarf’ and ‘TifEagle’ bermudagrasses [Cynodon dactylon(L.) Pers. × C. transvaalensisBurt Davy], ‘SeaDwarf’ seashore paspalum (Paspalum vaginatumSwartz), and ‘PristineFlora’ zoysiagrass [Zoysia japonicaStued. by Zoysia tenuifolia(L.) Merr.], sprigged at a rate of 36.6 m3ha−1on a USGA‐specified green, to compare grow‐in rate and qualitative turfgrass characteristics. Fertilizer treatments included 1.2, 2.4, 3.7, or 4.9 g N m−2wk−1, and a one‐time application of polymer‐coated urea (PCU) at 39.1 g N m−2, with each N rate coinciding with four N/K fertilization ratios: 1:1, 1:2, 1:3, or 1:4. Visual measurements of grow‐in rate were generally similar within cultivars with 2.4, 3.7, or 4.9 g N m−2wk−1There were no significant effects for turfgrass growth or quality among N/K treatments. The 2.4 g N m−2wk−1rate was considered best for rapid establishment of all cultivars. Although 1.2 g N m−2wk−1amended turfgrass was slower to establish, this rate provided a more desirable putting surface and further decreased the potential for nutrient leaching.

High‐yielding biomass crops remove significant quantities of soil nutrients, and nutrient replacement using inorganic fertilizers may not be sustainable. Municipal biosolids (MBS) are an alternative nutrient source. Organic N is the primary N form in MBS, and patterns of N mineralization can determine the effectiveness of MBS as an N source. The objectives of this experiment were to: (i) determine the effect of season of application on organic N mineralization rate and dry matter (DM) decomposition of Class A MBS measured in the field with litter bags and (ii) compare N mineralization measured using a field‐based technique with that predicted from the DECOMPOSITION model. Treatments were season of MBS application (spring and summer) during 2 yr. Organic N mineralization measured using litter bags followed the same pattern and arrived at a similar endpoint as predicted by the DECOMPOSITION model in three of four seasons. Lower spring temperatures and rainfall were associated with lower rates of N mineralization and DM decomposition during the 50 d following spring vs. summer application of MBS. When MBS were applied in summer, organic N mineralization leveled off approximately 50 d after application compared with 150 to 250 d following spring application. Seasonal weather conditions and N mineralization patterns should be considered when determining whether to apply MBS as the source of N, the timing of MBS application, and if single or split applications are best.

High‐yielding bioenergy crops remove large quantities of soil nutrients. Nutrients must be replenished in a manner that minimizes production costs and negative environmental impact. Class A municipal biosolids (MBS) were evaluated as an alternative nutrient source to inorganic fertilizer for ‘Merkeron’ and Chinese Cross elephantgrasses (Pennisetum purpureumSchum.) in a 2‐yr field experiment in Florida. Elephantgrass plots received 0, 33, 67, or 100% of total N applied (350 kg ha−1yr−1) from MBS, with the remainder from NH4NO3. Dry matter (DM) yield, tissue N and P concentrations and removal, and soil C and P concentrations were assessed. Elephantgrass yield decreased linearly from 24.2 to 20.1 (Merkeron) and 24.3 to 16.9 Mg ha−1(Chinese Cross) as the percentage of N supplied by MBS increased from 0 to 100. Nitrogen removal decreased from 208 to 127 kg ha−1yr−1over the same range of N from MBS. Phosphorus removal ranged from 28 to 43 kg ha−1yr−1, but the effect of N source was not consistent. There was no effect of percentage of N from MBS treatment on soil responses including water‐extractable (WEP), Mehlich‐1, or total P, nor was there an effect on total C concentration in the Ap horizon. Replacing 33% of N from inorganic fertilizer with N from MBS reduced elephantgrass biomass production 0 to 11%, so there is potential benefit to including MBS in a fertilization program for bioenergy crops, even in situations where MBS are limited to P‐based application rates.

Accumulation of organic matter (OM) at the soil surface (mat OM) and below (soil OM) can negatively affect putting green performance characteristics. The objective of this study was to evaluate cultural practices for control of OM and their effects on performance characteristics of a mature, USGA‐specified ultradwarf bermudagrass [Cynodon dactylon(L.) Pers. × C. transvaalensisBurt Davy] green in a subtropical climate. Two ultradwarf cultivars, ‘TifEagle’ and ‘Champion’, were subjected to hollow tine aerification (HTA) 1, 2, or 3 times yr−1, verticutting (VC) 3 times yr−1, solid tine aerification (STA) 5 times yr−1, and no treatment (control) for two consecutive years. Cultivars and treatments were arranged in a split‐plot, randomized complete block design. Although mat OM depth was similar among treatments, concentration was reduced after 2 yr by VC, HTA 2 times yr−1, and HTA 3 times yr−1. Solid TA (5 times yr−1) and hollow TA (2 and 3 times yr−1) reduced soil OM concentration compared with the control. Since VC also provided the highest turfgrass quality, firmest surface, least mower scalping, and least localized dry spots (LDS), it proved to be the best cultural practice tested, particularly since HTA 3 times yr−1increased saturated hydraulic conductivity (Ksat), which reduced volumetric water content and increased LDS. TifEagle was the better performing cultivar, as it had higher quality and less mower scalping.

Turfgrasses are commonly grown on a soil with a near neutral pH using synthetic organic slow‐release N sources which are more costly than soluble inorganic N materials. Acidic soil conditions slows nitrification and may decrease the long‐term leaching loss of inorganic NH+4source fertilizers, thereby increasing the N efficiency of the fertilizer source. Specific studies evaluating the effects of soil acidity on N fertilizer efficiency and turfgrass growth and thatch accumulation have not been conducted; therefore this study was initiated with the following objectives: (a) to assess the influence of acidity and N source on the quality, growth rate, N uptake, and thatch accumulation of Tifgreen bermudagrass [Cynodon transvaalensisBurtt‐Davis ✕ C. dactylon(L.) Pers.] and (b) to evaluate the effects of acidity on the retention of selected nutrients by the soil. Treatments were applied in a randomized complete block design with four replications to a 5‐year‐old Tifgreen bermudagrass turf growing on a loamy fine sand (Typic Quartzipsamment). Three N sources (Ammonium sulfate [AS], Isobutylidene diurea [IBDU], and activated sewage sludge [SS]) were applied at two frequencies (5 g and 10 g N m−2) every 14 and 28 days, respectively. The bermudagrass was rated every 14 days, clippings were collected every 45 days for growth rate and N uptake estimates and cores for thatch accumulation estimates were collected after each of three growing seasons. Maximum growth rates occurred at pH less than 4.0. Overall turfgrass quality was not significantly influenced by N source or frequency of application. Acidity promoted thatch accumulation, except in the presence of applied Ca. Significantly lower levels of thatch accumulated on plots receiving IBDU. Application of 5 g N m−2as AS every 14 days promoted the accumulation of more thatch than 10 g N m−2applied every 28 days. Frequency of application had no effect on the thatch accumulation of plots receiving IBDU and SS. Mehlich I extractable nutrients (P, K, Ca, and Mg) in the top 5 cm of soil declined with increasing levels of acidity. Turfgrass growth rate was not reduced in the presence of a 100 to 1 soil extractable Ca to Mg ratio.

Relatively little information is available on the effects of liming on roots as compared with tops. To study the effect of various Al saturations on the growth of tops, roots, nodules, and nutrient accumulation of soybeans (Glycine maxL.), several rates of lime were added to an acid soil in a greenhouse experiment. Dry weight of tops increased as the Al saturation was decreased by liming. Total dry weight and length of roots were unaffected by the soil treatments. Primary root weight was increased by liming. Root morphology, however, changed in that the lateral root weight decreased and the length per gram fresh weight of lateral root increased with decreasing Al saturation. Liming promoted the formation of a larger number of small diameter lateral roots. Nodulation, best expressed by nodule number, increased with liming and was highly correlated with the Ca content of the primary root. Top dry weight was significantly correlated with the K concentration of the tops, Ca and Al concentration of the nodules, Mg concentration of the root mass, and the Zn concentration of the primary root. Total uptake/cm of root and equivalent elemental ratios were not as highly correlated with growth as concentration. Nodule number was significantly correlated with the total Ca and P content of the primary root, total P and Mg content of nodules, and the Ca/Al ratio of the nodule.

The generalization is often made that tropical legumes show little or no response to lime, even in acid soils low in Ca. Phosphorus responses, however, are generally observed. The effect of lime in an acid, virgin spodosol (Oldsmar fs) in southern Florida plots was investigated. Significant yield responses to lime and P were observed. Maximum total annual dry matter production of centro (Centrosema pubescensBenth.), desmodium (Desmodium heterocarponDC.), stylo (Stylosanthes guyanensisSwartz), and ‘Siratro’ (Macroptilium atropurpureumUrb.) required lime applications of about 2,200 kg/ha. Regression analyses suggested that centro and Siratro might respond to higher lime rates if combined with P rates higher than those used in the study. Calculated optimum P rates ranged from 45 to 78 kg/ha, with desmodium requiring the least. Liming beyond the optimum rate appeared to seriously reduce production of desmodium and stylo.

Growth of soybean [Glycine max(L.) Merr.] roots into acid subsoils and utilization of subsoil moisture is limited in many soils of the southeastern U. S. because of Al toxicity. Laboratory and greenhouse experiments were conducted to obtain information on tolerance of soybean cultivars which would be helpful in selection of cultivars best adapted to acid subsoils. Root elongation measurements were made of 18 cultivars exposed for 48 hours to solutions containing 0, 0.25, 0.50, and 1.0 ppm Al and 10 ppm Ca. Eleven of the cultivars were selected for a greenhouse experiment in which plants were grown in a Lynchburg soil (Aerie Paleaquult) at 81 and 4% Al saturation. Measurements were made of top growth, root length, and the Ca, P, and Al concentrations of the plant tissue. Of the 11 cultivars used, ‘Lee’, ‘Lee 68’, ‘York’, ‘Ogden’, and ‘Dare’ were judged to be relatively Al tolerant according to the short term root elongation studies. Based on absolute top growth in the 81% Al saturated soi1 or relative top growth in the 81% Al saturated soil as compared with the 4% Al saturated soil the cultivars Lee, ‘Bragg’, ‘Pickett 71’, and York were more tolerant of Al than the other cultivars.

This study was initiated to evaluate the effect of N fertilization rate on the P, K, and Mg requirements of ryegrass (Lolium perenneL.) and bermudagrass (Cynodon dactylon(L.) Pers. X Cynodon transvaalensisBurtt Davy) and to determine the N fertilization requirements of the two turfgrasses. Information gained through this research will be of particular benefit to producers of cool and warmseason turfgrasses on golf courses of the southeastern USA. During the fall ‘Medalist II’ (a mixture of Pennfine and NK100 cultivars) perennial ryegrass was seeded over ‘Tifway’ bermudagrass growing on a loamy fine sand (Typic Quartzipsamment). Treatments were applied in a split‐plot arrangement in plots 1.83 ✕ 2.73 m and replicated five times. Nitrogen was applied as ammonium nitrate at 2.5 g N/m2every 1, 4, and 8 weeks to establish the rates of 20, 5 and 2.5 g N/m2/8 weeks, respectively. Four subplot treatments were applied every 12 weeks using 5, 10, and 5 g/m2of P, K, and Mg, respectively, as a complete treatment. The three additional treatments were established by excluding one of the three nutrients, respectively. The turfgrasses were mowed at 3‐day intervals. Harvests for yields occurred biweekly and consisted of 3‐day growth of the grasses. Ten harvests were collected per grass species per growing period. The study extended over two growing periods for each grass species and a total of 40 harvests. The two lower N rates (2.5 and 5.0 g/m2/8 weeks) were not adequate to maintain acceptable turfgrass quality. A higher incidence of disease and a lower quality turf resulted from these treatments. Tifway bermudagrass had a higher dry matter yield rate than Medalist II ryegrass at a given N percentage and grew faster at each level of N applied. Ryegrass responded to P on this soil which contained a minimum of 82 ppm double‐acid (0.025NH2SO4in 0.05NHCl) extractable P. Contrarily, bermudagrass produced the highest yield when P was excluded. Both grasses were reduced in yield by exclusion of K at the high N rate. The minimum double‐acid extractable K level was 33 ppm. Ryegrass accumulated more N, P, K and Mg at each level of N fertilization than bermudagrass. Excluding P tended to reduce the N percentage in ryegrass tissue, but increased the N percentage in bermudagrass. A level of 60 ppm double‐acid extractable Mg was adequate for growth of both grasses even though the Ca:Mg ratio in some cases exceeded 20:1.

The influence of clipping return on bermudagrass thatch has not been resolved. Additionally, independent and combined effects of applied Ca, Mg, and K on bermudagrass growth and quality and thatch accumulation have not been clarified. To evaluate the influence of clipping return and applied Ca, Mg, and K on ‘Tifway’ bermudagrass (Cynodon dactylon(L.) Pers. × Cynodon transvaalensisBurtt Davy) and ‘Pennant’ perennial ryegrass (Lolium perenneL.) a 3‐y study was conducted at the Turfgrass Field Laboratory near Gainesville, FL, on an Arredondo loamy fine sand (Typic Quartzipsammets). A strip‐split‐plot factorial experiment with applied Ca, Mg, and K at 20 g m−2representing the main plot and with clipping return or removal stripped across the main plots with three replications was employed. Bermudagrass clipping return did not affect overall mean thatch accumulation. Bermudagrass and perennial ryegrass clipping yields increased in response to clipping return. Bermudagrass quality was enhanced by the return of clippings, but ryegrass quality was not. Application of Ca and K did not influence thatch accumulation, while Mg did promote additional bermudagrass thatch. Application of K and Mg reduced Ca levels on plots receiving Ca to less than the extractable Ca level of the untreated plots. Ryegrass and bermudagrass quality was increased by the application of Mg on plots which had the clippings removed. Potassium and Mg application promoted bermudagrass clipping yield when clippings were removed. Soil Ca to Mg ratio did not influence the growth or quality of either bermudagrass or ryegrass.

In a pot‐culture experiment with four highly‐thatched turfgrasses [bermudagrass, Cynodon dactylon(L.) Pers.; centipedegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensisL.; and St. Augustinegrass, Stenotaphrum secundatum(Walt.) Kuntze] we examined the influence of selected white‐rot fungi and topdressings on the degradation of thatch components. Cores of each turfgrass were placed in pots and inoculated with one of four species of white‐rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inoculation and after the 6 month sampling. Subplot treatments of the split‐plot design were three topdressings (none, 0.31 cm sand, and 0.31 cm sand containing 4% colloidal phosphate). Samples of thatch were collected 6 and 12 months after inoculation and analyzed for cellulose and lignin by the acid detergent fiber procedure. Total oxidizable organic material and C and N were also determined. The cellulose content of bermudagrass and centipedegrass thatch was significantly reduced by Phebia gigantea, but no fungus significantly reduced the thatch cellulose content of St. Augustinegrass and Kentucky bluegrass. Coriolus versicolorsignificantly reduced the lignin content of thatch from all turfgrass species and the total oxidizable organic material of bermudagrass and centipedegrass. It appears to hold some potential for decomposing accumulated thatch. Topdressings with sand or a mixture of sand and colloidal phosphate significantly reduced the cellulose and lignin contents of thatch from most of the turfgrass species. Adding colloidal phosphate to the sand did not significantly increase the decomposition rate of the thatch. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose.

A small amount of information is available on the effects of Al saturation on the nutrient concentration of different plant components. This manuscript presents data showing the former relative to the soybean [Glycine max(L.) Merr.]. To study the effects of varying exchangeable Al saturation on the concentration of P, Ca, Mg, and Al in the tops, primary roots, lateral roots, and nodules of soybeans, a randomized complete block greenhouse experiment using 12 soybean cultivars and three soil Al saturation levels was established. The soil was a Lynchburg sandy loam (Aeric Ochraquult). Soil Al saturation levels were established by adding various amounts of lime. Soil Al saturation had no effect on the P concentration of the tops. Root P concentration was significantly higher at 81% Al saturation than at 28 and 4%. Nodules had a much higher P concentration than the other plant parts. The calcium concentration of all plant parts was increased with increasing additions of CaCO3. Tops contained the highest Ca concentration and nodules the lowest. Aluminum saturation levels of 81 and 28% did not significantly affect the Mg concentration of the tops and primary roots. The Mg concentration of the nodules decreased as AI saturation decreased due primarily to a dilution effect. Tops and nodules contained approximately twice as much Mg as the root components. Top and root Al concentration was reduced by 53 and 30%, respectively, when the Al saturation was reduced from 81 to 28%. Aluminum concentration of tops was 6, 2, and 8% of the primary roots, lateral roots, and nodules, respectively at 81% Al saturation. Top growth and nodule number increased as the Al saturation was reduced from 28 to 4%, however, very little change occurred in the Al concentration of the tops over this range. Thus, growth responses of soybeans to reduction of soil Al saturation below 28% appears to be due to pH effects and/or Ca supply.