Current emphasis on writing comprehensive nutrient management plans for crop production in the mid-Atlantic region of the United States requires accurate crop nutrient removal values for vegetable crops. Therefore, studies were conducted to measure nutrient uptake in harvested fresh sweet corn (Zea mays) ears in 2003 on a sandy loam soil and in 2004 on a silt loam soil, in New Jersey. Nine varieties were included in the study to represent early, mid-, and late-season hybrids. Corn production practices followed local extension recommendations. The crop was seeded by hand and thinned to ensure a uniform within-row spacing of 9 inches and a population of 23,231 plants/acre. Nutrient concentrations were determined on ear and stover samples oven-dried at 70 °C for 72 hours. Mean nutrient uptake values for full-season varieties based on a typical sweet corn yield of 150 cwt/acre (about 18,396 ears/acre) would be projected to remove (in lb/acre) 51 N, 9.1 P, 34 K, 3.7 S, 2.0 Ca, 3.9 Mg, 0.024 B, 0.09 Fe, 0.044 Mn, 0.014 Cu, and 0.072 Zn. Values for N, P, and K are similar to reference values in Knott's Handbook for Vegetable Growers (4th ed.). Due to smaller ear size, nutrient removal values were generally lower for early and mid-season varieties. In 2004 only, nutrient removal by harvesting the crop residue was also determined by assuming a harvest of 23,231 plants/acre, minus the upper ear for the average full-season hybrid. This biomass was found to remove (in lb/acre) 126 N, 13.4 P, 173 K, 11.6 S, 20.6 Ca, 13.6 Mg, 0.05 B, 0.37 Fe, 0.30 Mn, 0.05 Cu, and 0.13 Zn.
In-season soil nitrate testing is most useful when there is reason to believe, based on field history, that N availability may be adequate. These reasons may include soil organic matter content, applied manure, compost, legumes in the rotation, or residual N fertilizer. Soil nitrate testing is not helpful when crops are grown on sandy, low organic matter content soils that are known from experience to be N deficient. Soil nitrate testing is useful for annual crops such as vegetables or corn for which supplemental N fertilization is a concern. Soil nitrate tests must be performed at critical crop growth stages, and the results must be obtained rapidly to make important decisions about the need for N fertilization. Soil nitrate-N (NO3-N) concentrations in the range of 25 to 30 mg·kg-1 (ppm) indicate sufficiency for most crops, but N fertilizer practice should be adjusted based on local extension recommendations.
H. Liu, J.R. Heckman and J.A. Murphy
The fine fescues are generally considered to be acid-tolerant compared to many other cool-season turfgrasses. However, there is a lack of documentation on aluminum tolerance of fine fescues at both the species and cultivar levels. A total of 58 genotypes belonging to five species or sub-species were screened under greenhouse conditions using solution culture, sand culture, and acid Tatum subsoil. This soil had 69% exchangeable Al and a pH of 4.4. An Al concentration of 640 μM and a pH 4.0 were used in solution screening and sand screening. Differences in Al tolerance were identified at both species and cultivar levels based on relative growth. The genotypes with endophyte infection generally exhibited greater Al tolerance than endophyte-free genotypes. The results indicate that fine fescues vary in Al tolerance and there is potential to improve Al tolerance with breeding and to refine management recommendations for fine fescues regarding soil pH.
J. R. Heckman, D. J. Prostak and W. T. Hlubik
The presidedress soil nitrate test (PSNT) is an in-season soil test that evaluates the N supplying capacity of soil before side dressing to adjust N application rates. Increasing acceptance of this soil test among field corn growers in New Jersey has shown it to be an effective practice. Nitrogen application rates were reduced by an average of 45 kg-1 ha without loss of crop yield. Field calibration research to extend use of the PSNT to sweet corn has the potential to improve N fertilizer recommendations for this crop. A critical concentration of 25 mg kg-1 NO3-N in the surface 30 cm of soil is generally considered adequate for field corn. Certain crop features of sweet corn (earlier harvest, smaller plant size and population) suggested that the critical NO2-N level might be lower than for field corn while market quality suggested that it might be a higher value. Results from 40 sweet corn field calibration sites in New Jersey indicate that the PSNT critical soil NO3-N concentration may be greater for sweet corn than field corn. A preliminary critical level of 30 mg kg-1 NO3-N in the surface 30 cm of soil is suggested for use of the PSNT on sweet corn. Further research is being conducted to improve sidedress N recommendations based on the PSNT.
J.R. Heckman, G.C. Pavlis and W.L. Anastasia
In New Jersey, the major soil series (Sassafras, Pocomoke, Berryland, Atsion, and Downer) used for blueberry (Vaccinium corymbosum L.) production often have soil pH levels much lower than the soil pH range of 4.0 to 5.2 that is considered satisfactory for blueberry. The lime requirements for these soils to achieve a target soil pH of 4.8 has not been established. Soils with current soil pH levels in the range of 3.3 to 3.9 were collected from eight New Jersey sites used for blueberry production. The soils were treated with various application rates of calcium carbonate (CaCO3) and incubated in a green-house to estimate the lime requirement of each soil. After 70 days of incubation with CaCO3, results show that a general lime recommendation of 100 lb of calcium carbonate equivalent (CCE)/acre (112 kg·ha-1) for each one tenth of a soil pH unit increase desired would elevate pH of each of the soils to within a range (pH 4.3 to 5.0) that brackets the target pH of 4.8 without causing serious risk of overliming.
J.R. Heckman, W.T. Hlubik, D.J. Prostak and J.W. Paterson
Research was conducted with sweet corn (Zea mays L.) to evaluate the presidedress soil NO3 test (PSNT) originally developed for use on field corn on a wide range of New Jersey soils. Soil NO3-N concentrations reflected differences in N availability due to manure or preplant N application. The relationship between soil NO3-N concentration and relative yield of marketable ears was examined using Cate–Nelson analysis to define the PSNT critical level. Soil NO3-N concentrations >25 mg·kg–1 were associated with relative yields at ≥92%. The success rate for the PSNT critical level was 85% for predicting whether sidedress N was needed. Including NH4-N in the soil analysis did not improve the accuracy of the soil test for predicting whether sidedress N was needed. Although the PSNT is quite accurate in identifying N-sufficient sites, it appears to offer only limited guidance in making N-fertilizer rate predictions. The PSNT is most useful on manured soils, which frequently have sufficient N. The test likely will help decrease the practice of applying “insurance” fertilizer N and the ensuing potential for NO3 pollution of the environment.
W.J. Hill, J.R. Heckman, B.B. Clarke and J.A. Murphy
Take-all patch, caused by Gaeumannomyces graminis (Sacc.) Arx. & D. Olivier var. avenae (E.M. Turner) Dennis (Gga), is a disease of creeping bentgrass (Agrostis stolonifera Huds.), which most often is associated with golf courses. Synthesis of ligneous and phenolic compounds by plants requires adequate Mn+2 and Cu+2 nutrition and may be a factor in disease resistance. An experiment was conducted on a creeping bentgrass fairway naturally infested with Gga to determine if foliar applications of Mn+2 (1.02 and 2.04 kg·ha–1 per application) and Cu+2 (0.68 kg·ha–1 per application) would reduce take-all severity. Prior to initiating treatments, soil pH was 6.4 and Mehlich-3 extractable Mn+2 and Cu+2 were 5 mg·kg–1 and 1.7 mg·kg–1, respectively. Manganese and copper sulfate treatments were initiated in July 1995 and foliarly applied every 4 weeks through 1997 with the exception of December, January, and February. Disease incidence was decreased from 20% on untreated turf to 5% with the high rate of MnSO4. For both years, turf treated with the high rate of Mn+2 had less disease than turf receiving the low rate of Mn+2. The application of CuSO4, however, did not influence disease development.
Joseph R. Heckman, Thomas Morris, J. Thomas Sims, Joseph B. Sieczka, Uta Krogmann, Peter Nitzsche and Richard Ashley
The pre-sidedress soil nitrate test (PSNT) was evaluated in 27 fields in New Jersey, 6 in Connecticut, 5 in Delaware, and 2 on Long Island in New York for its ability to predict whether sidedress N is needed to grow fall cabbage (Brassica oleracea var. capitata) as a double crop. Soil NO3-N concentrations measured on 20 field sites on the day of transplanting and 14 days after transplanting indicated that NO3-N concentrations over this time period increased, and that residues from the previous crop were not causing immobilization of soil mineral N. The relationship between soil NO3-N concentration measured 14 days after transplanting and relative yield of marketable cabbage heads was examined using Cate-Nelson analysis to define the PSNT critical level. Soil NO3-N concentrations ≥24 mg·kg-1 were associated with relative yields >92%. The success rate for the PSNT critical concentration was 84% for predicting whether sidedress N was needed. Soil NO3-N concentrations below the PSNT critical level are useful for inversely adjusting sidedress N fertilizer recommendations. The PSNT can reliably determine whether fall cabbage needs sidedress N fertilizer and the practice of soil NO3-N testing may be extendable to other cole crops with similar N requirements.