Phosphorus is considered to be the major factor causing eutrophication of Lake Okeechobee and other waterways in Florida. An important source of P for Lake Okeechobee is runoff of soluble P ...fertilizer applied to bahiagrass (Paspalum notatum Flugge) pastures. A study was conducted to ascertain whether P application levels could be reduced below current agronomic recommendations without affecting pasture yields or quality and to determine the effects of P application on surface water quality. A field study was conducted on a bahiagrass pasture to assess the yield response of bahiagrass to five annual rates of P (0, 6, 12, 24, and 48 kg ha-1) and two application times (dry season and wet season). Fertilizer treatments were arranged in a randomized complete block design with four replications on an Immokalee fine sand (sandy, siliceous, hyperthermic Arenic Haplaquods). Results indicate that P fertilization rates could be reduced from 48 to 24 kg P ha-1 without affecting yields or quality of bahiagrass. Yields in 1989 averaged 11.4, 14.7, and 10.4 Mg ha-1 for the 48, 24, and 0 kg P ha-1 treatments, respectively. Time of P application had no effect on yields or quality of bahiagrass. There was a linear increase in Mehlich I extractable P in the A and E horizons and a quadratic increase to P in the Bh horizon in 1989. Extractable P ranged from 3.8 to 22.5, 1.3 to 2.5, and 21 to 55 mg P kg-1 for the A, E, and Bh horizons, respectively. Phosphorus concentrations in surface water runoff was reduced from 33 to 60% as P application rates were decreased from 48 to 12 kg P ha-1 while total P loss was reduced from 17 to 78%, respectively. Recommended reductions in P application should result in substantial cost savings to producers and also reduce P inputs into surface water
Bahiagrass (Paspalum notatum Flugge) pasture fertilization recommendations have traditionally been based upon clipping studies. Inclusion of P from manure, not originally considered when P ...recommendations were developed for pastures, may minimize the need for P fertilization without reducing bahiagrass production or P uptake. The objective of this research was to determine if manure contributes greatly to the P crop nutrient requirement. A 2-year field study utilized a factorial arrangement of 0 and 6.9 Mg air-dried manure ha-1 with 0, 17, 34, 51, and 68 kg inorganic P ha-1 from triple superphosphate to evaluate bahiagrass yield, root distribution, and P uptake response on a Myakka fine sand (sandy, siliceous, hyperthermic Aeric Alaquod). Because air-dried manure was used in the field study, a greenhouse study was employed to confirm that there were no differences in bahiagrass yield or P uptake from either air-dried or fresh cattle (Bos spp.) manure sources. There were no manure or manure by P interaction effects on yield or P uptake of bahiagrass indicating that manure source did not effect grass production in the greenhouse. In the field study, bahiagrass roots were distributed into the Bh horizon, and the Bh horizon had at least four times more Mehlich-1 extractable P than that of the Ap horizon. This horizon was most likely acting as a main source for P-uptake by the grass. This observation was further confirmed by no yield response to levels of inorganic P application in 1989. A linear-response-and-plateau (R2=0.196) relationship with a critical point of 15.4 kg P ha-1 was found in 1990. Bahiagrass yield and P uptake were not dependent on P fertilization, either from manure or inorganic P, due to the availability of P from the Bh horizon.
Liming of soil to attain a target pH of 5.5 has been believed to be an essential practice of bahiagrass (Paspalum notatum Fluegge) management. A study was conducted to evaluate the response of ...bahiagrass grown on a virgin Ona fine sand (sandy, siliceous, hyperthermic Typic Haplaquod) of pH 4.5 to application of either calcitic limestone (0, 1.1, 2.2, 3.3, 4.4, or 6.6 Mg ha-1) or phosphogypsum (2.2 or 4.4 Mg ha-1). 'Pensacola' bahiagrass was seeded in August 1987. Treatments were replicated four times in a randomized complete-block design. Although the addition of 6.6 Mg lime ha-1 increased soil solution pH from 4.5 to 6.0 and decreased the activity of monomeric Al from 45 to 17 micromolar, root growth down to the 90-cm sampling depth and dry matter yields during 3 yr were not improved by liming. Application of phosphogypsum also reduced both root growth and dry matter yields. Soil pH (0-15 cm) 41 mo after the application of various amendments averaged 4.5 for the control, 4.2 for the 4.4 Mg phosphogypsum ha-1 treatment, and 6.0 for the 6.6 Mg limestone ha-1 treatment. Soil pH averaged 5.1 and 5.2 at the 45- to 60- and 75- to 90-cm depths, respectively, regardless of treatments. Exchangeable Al averaged 35.4 mg kg-1 at the 0- to 15-cm depth and 23.4 mg kg-1 at the 75- to 90-cm depth in unamended treatments. Aluminum saturation in 1990 ranged from 48.2 to 85.5% on the control plots. Lime application decreased exchangeable Al and Al saturation percentage by 10-fold in the upper 15 cm. This study showed no significant increases in forage yield of bahiagrass from increasing the soil pH above 4.5
Phosphorus is considered to be the major factor causing eutrophication of Lake Okeechobee and other waterways in Florida. An important source of P for Lake Okeechobee is runoff of soluble P ...fertilizer applied to bahiagrass (
Paspalum notatum Flugge) pastures. The present study was conducted to ascertain whether P application levels could be reduced below current agronomic recommendations without affecting pasture yields or quality and to determine the effects of P application on surface water quality. A field study was conducted on a bahiagrass pasture to assess the yield response of bahiagrass to five annual rates of P (0, 6, 12, 24 and 48 kg ha
−1) and two application times (dry season and wet season). Fertilizer treatments were arranged in a randomized complete block design with four replications on an Immokalee fine sand (sandy, siliceous, hyperthermic Arenic Haplaquods). Results indicate that P fertilization rates could be reduced from 48 to 24 kg P ha
−1 without affecting yields or quality of bahiagrass. Yields in 1989 averaged 11.4, 14.7 and 10.4 Mg ha
−1 for the 48, 24 and 0 kg P ha
−1 treatment, repectively. Time of P application had no effect on yields or quality of bahiagrass. There was a linear increase in Mehlich I extractable P in the A and E horizons and a quadratic increase to P in the Bh horizon in 1989. Extractable P ranged from 3.8 to 22.5, 1.3 to 2.5, and 21 to 55 mg P kg
−1 for the A, E and Bh horizons, respectively. Phosphorus concentrations in surface water runoff was reduced from 33 to 60% as P application rates were decreased from 48 to 12 kg P ha
−1 while total P loss was reduced from 17 to 78%, respectively. Recommended reductions in P application should result in substantial cost savings to producers and also reduce P inputs into surface water.
Bahiagrass (Paspalum notatum Flugge) is grown on more pasture land in Florida than all other pasture-grasses combined. Despite the large amount of bahiagrass grown annually, there is a surprising ...lack of information concerning the nutrient requirements of bahiagrass-pastures. Currently, fertilizer recommendations for all nutrients, especially micronutrients. The Diagnosis and Recommendation Integrated System (DRIS) was developed to make an interpretation from the results of the chemical analysis of a plant tissue sample from which an accurate fertilizer recommendation could be made. The DRIS represents a holistic approach to interpreting tissue analyses. This study was conducted to develop DRIS norms for bahiagrass-pastures and to evaluate the accuracy of those norms. A database, from which the DRIS norms were determined, was assembled by collecting 857 bahiagrass-pasture samples from ongoing bahiagrass field fertility trials located in nine counties throughout central Florida and analyzing the samples for N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu. At the time of sampling, forage yields were also determined. When DRIS norms were applied to data from an independent study in which bahiagrass was grown in greenhouse solution culture, known nutrient deficiencies were accurately diagnosed. The nutrients limiting bahiagrass forage yields in a fertility trial conducted under field conditions were also correctly identified by the DRIS interpretation of the tissue analyses. The results obtained during this study indicate that the DRIS can be successfully applied to bahiagrass grown and sampled under a wide range of conditions. Therefore, it appears that the DRIS developed for bahiagrass can provide very useful information from which nutrient deficiencies can be readily and correctly identified and more accurate fertilization programs can be developed for bahiagrass-pastures
