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  • Author or Editor: John Howell x
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Guidelines for the use of the pre-sidedress soil nitrate test (PSNT) have been established in sweet corn (Zea mays). Similar guidelines should be useful to growers in optimizing nitrogen (N) use in other vegetables. The purpose of this work was to establish a soil N threshold for butternut squash (Cucurbita moschata), above which there is no positive crop response to additional N application. To test crop response to sidedress applications of N over a range of soil nitrate levels, plots were established in pairs in commercial butternut squash fields. Six-inch sample cores for the PSNT were taken several days prior to sidedressing, which is about the time the vines start to run. Sidedress N applications were made by the grower. In each field, one plot received no N and the other received N at 50 kg·ha-1. The yield of the plot with the N treatment was compared with the nontreated plot. In fields where the PSNT values were at or above 68 mg·kg-1 N, plots receiving sidedress N had lower yields than those receiving no N. In fields with N levels at 41 mg·kg-1 or lower, there generally was a higher yield in the sidedressed plots. None of the fields in this study had N levels between 41 and 68 mg·kg-1 at the time of sampling, but it is likely that the threshold is within this range. E-mail howell@umext.umass.edu

Free access

Hot cherry peppers were grown after incorporation of the following three winter cover crop regimes in Summer 1994—hairy vetch (Vicia villosa) plus winter rye (Secale cereale), hairy vetch alone, and no cover crop. For each main effect there were three N rates applied to peppers in three applications over the course of the season: 0, 85, and 170 kg·ha–1. The pepper yield was significantly higher with hairy vetch plus rye than rye alone or no cover crop. There was also no significant yield increase with the addition of N fertilizer to the peppers grown with hairy vetch. Soil nitrate–N levels taken just prior to N sidedress were significantly higher in plots that had hairy vetch plus rye compared to other treatments. There was also a significant linear relationship of the soil nitrate–N levels among the three N rates. Based on the results of this study, sidedressing peppers would be recommended when soil nitrate levels are above the 25 ppm that is the current threshold for other crops. SPAD readings were taken several times during the season. There was a high correlation of SPAD readings to pepper yield very early and very late in the season. The correlation of SPAD readings to pepper yield was poorest when taken at the time of N sidedress.

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Abstract

Growth of ‘Jewel’ sweet potato [Ipomoea batatas (L.) Lam.] plants was increased significantly by black plastic mulch. Leaf area, number of leaves, and total shoot dry weight were significantly larger for mulched than for unmulched plants. Marketable root yield was increased significantly by black plastic mulch and raised beds. The highest root yield (18.6 MT/ha) was obtained from mulch-covered raised beds.

Open Access

The effects of transplant depth on lodging and yield were evaluated in five experiments in Florida and Massachusetts. `Cherry Bomb', `Jupiter', and `Mitla' pepper (Capsicum annuum L.) transplants were set at three depths so that the soil surface was even with the top of the rootball, the cotyledon leaf, or the first true leaf. Seedlings set to the depth of cotyledon leaves or to the first true leaf lodged less than did those set to the top of the rootball. No yield differences were recorded among treatments in Massachusetts; however, total weight of red fruit was greater in treatments that lodged less in 1 of the 2 years, suggesting that lodging delayed maturity. Soil temperature in Massachusetts declined at the level of the rootball as planting depth increased.

Free access

Abstract

The yield of inflorescences and essential oil of ‘Dutch’ lavandin (Lavandula x intermedia Emeric ex Loisel.) was increased significantly with the addition of a 2.5-cm topdressing of white sand. Fertilization did not increase yields on a near-optimally fertile soil.

Open Access