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- Author or Editor: Joseph R. Heckman x
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Sweet corn (Zea mays L.) growers evaluating new practices for N management, such as the presidedress soil nitrate test (PSNT), are interested in relating observations about crop performance at time of harvest to their N fertility program. For this purpose, the concentration of nitrogen (N) in the lower portion of sweet corn stalks was examined on the day of harvest as a basis for evaluating the crop N status. Sweet corn stalk tissue was collected from N-rate experiments by cutting a stalk section at 15 and 35 cm aboveground and removing leaf material from the resulting 20-cm segment. Samples were dried and analyzed for total Kjeldahl N. Relationships between crop yield and stalk N concentration indicated that concentrations <11 g·kg-1 are N deficient and underfertilized; N concentrations between 11 and 16.5 g·kg-1 are marginally deficient; and between 16.5 and 21 g·kg-1 the N status is optimum. Concentrations of N >21 g·kg-1 are above optimum and indicate that sweet corn was overfertilized with N. When soil nitrate concentrations (PSNT >25 mg NO3-N per kilogram) indicated sufficient N at time of sidedressing, stalk N concentrations generally indicated N sufficiency at harvest.
Field experiments were conducted with Cucurbita pepo L. `Howden' pumpkin in 2000 to 2001 to study the effects of silicon (Si) amendment of soil with and without the use of fungicides on yield and powdery mildew suppression. A Quakertown silt loam soil (fine-loamy, mixed, mesic Typic Hapludult) with an initial soil pH of 5.7 was amended with either CaCO3 or CaSiO3 at the rate of 7840 kg·ha-1 of calcium carbonate equivalent. Fungicides were applied on a 7-10 day schedule to half of the plots as a 2 × 2 factorial, beginning when the first powdery mildew lesions were detected in the field. Silicon amendment increased pumpkin yield by 60% in 2000 but Si did not influence yield in 2001. Infection with bacterial leaf spot reduced yield on all plots in 2001. Fungicide applications increased yield only in 2001. In 2000, Si amendment had the effect of delaying foliage senescence but it was not clear if this was the result of an effect of Si on disease activity or crop physiology. In Aug. 2001, Si amendment generally reduced powdery mildew severity, but only at the 10% level of significance. In Sept. 2001, the combination of Si amendment plus fungicide application was more effective in reducing powdery mildew severity than either Si or fungicide alone. Silicon amendment resulted in a 5-fold increase in plant Si concentration. Soil pH measured after harvest in 2001 indicated no significant difference in pH between plots amended with CaCO3 (pH = 6.8) and CaSiO3 (pH = 6.9). In New Jersey, the cost of these liming materials is similar. Thus, the selection of CaSiO3 as a liming material as needed for soil pH correction has the potential benefits of suppressing powdery mildew and increasing pumpkin yield without increasing the cost of production.
Recent changes in soil testing methodology, the important role of P fertilization in early establishment and soil coverage, and new restrictions on P applications to turf suggest a need for soil test calibration research on Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb), and perennial ryegrass (Lolium perenne L.). Greenhouse and field studies were conducted for 42 days to examine the relationship between soil test P levels and P needs for rapid grass establishment using 23 NJ soils with a Mehlich-3 extractable P ranging from 6 to 1238 mg·kg–1. Soil tests (Mehlich-1, Mehlich-3, and Bray-1) for extractable P were performed by inductively coupled plasma–atomic emission spectroscopy (ICP). Mehlich-3 extractable P and Al were measured to evaluate the ratio of P to Al as a predictor of need for P fertilizer. Kentucky bluegrass establishment was more sensitive to low soil P availability than tall fescue or perennial ryegrass. Soil test extractants Mehlich-1, Bray-1, or Mehlich-3 were each effective predictors of need for P fertilization. The ratio of P to Al (Mehlich-3 P/Al %) was a better predictor of tall fescue and perennial ryegrass establishment response to P fertilization than soil test P alone. The Mehlich-1, Bray-1, and Mehlich-3 soil test P critical levels for clipping yield response were in the range of 170 to 280 mg·kg–1, depending on the soil test extractant, for tall fescue and perennial ryegrass. The Mehlich-3 P/Al (%) critical level was 42% for tall fescue and 33% for perennial ryegrass. Soil test critical levels, based on estimates from clipping yield data, could not be determined for Kentucky bluegrass using the soils in this study. Soil testing for P has the potential to aid in protection of water quality by helping to identify sites where P fertilization can accelerate grass establishment and thereby prevent soil erosion, and by identifying sites that do not need P fertilization, thereby preventing further P enrichment of soil and runoff. Because different grass species have varying critical P levels for establishment, both soil test P and the species should be incorporated into the decision-making process regarding P fertilization.
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.
Annie’s Project: Farming in New Jersey’s Cities and the Urban Fringe focused on the following five areas of risk identified by the US Department of Agriculture Economic Research Service: financial, production, marketing/price, legal/institutional, and human/personnel. Additional education regarding urban farming topics included securing suitable land, dealing with contaminated soils and alternative growing medias, and securing water for crop production. We delivered a series of six 3-hour evening classes to 23 producers. We administered a retrospective evaluation at the conclusion of the series and distributed an evaluation survey 6 months after training. Both evaluations found that participants increased their understanding of farm risks. Furthermore, they indicated they were better able to manage the impacts of the COVID-19 pandemic on their farm business activities.