Onions

Overwinterd Onion Variety Trials, 1980-1982

The purpose of these experiments was to evaluate the performance of several onion (Allium cepa L.) cultivars in overwinter trials. The Willamette Valley appears to have a suitable climate for production of overwintered onions if bolting, disease, and weed control problems can be overcome. Previous experiments at the North Willamette Station have indicated that late August or early September planting dates are superior to later planting dates for maximum yields. With a June or July harvest, this might allow another crop on the onion ground both before planting and after harvest.

Lime and Fertilizer Effects on Spring-Planted Onions (1984)

Fertilizer trials with overwinter onions at the North Willamette Station have shown a strong onion yield response to application of lime and gypsum and, in one experiment, a higher yield with ammonium sulfate rather than ammonium nitrate as N source. The yield response to gypsum and ammonium sulfate indicates that when soil pH, P, K, and N are optimal, S may be the element most limiting to onion bulb development. The following trial was designed to investigate the effects of lime, gypsum, and form of N on spring-seeded onions.

Methods

Lime and Fertilizer Effects on Overwintered Onions (1984)

Overwintered onions in the Willamette Valley are seeded in early September and harvested in the following spring or summer. Obtaining strong and early growth in the spring is essential to achieve large bulb size and profitable yields. However, soil and air temperatures are usually less than optimal during the spring growth period, possibly limiting response to fertilizers.

Lime and Gypsum Effects on Spring-Planted Onions (1986)

Fertilizer trials with overwintered onions at the North Willamette Station indicated a strong yield increase with application of lime, an increase with gypsum (calcium sulfate), and higher yields with ammonium sulfate rather than other N sources. The yield response to gypsum and ammonium sulfate indicated that when soil pH, N, P, and K are optimal, S may be the limiting element in onion production.

Nitrogen Rates and Phosphorus on Onions (1986)

Storage onions in western Oregon have been grown almost exclusively on lake bottom soils which are high in organic matter (more than 10%). Recently, production of onions on mineral or "upland" soils with low organic content and N availability has increased rapidly and now equals production on the organic soils. Response of onions to nitrogen rate and to applications of phosphorus and potassium on the mineral soils is not well understood.

Row Covers on Overwintered Vegetables (1988)

Introduction

Overwintered vegetables, seeded in late summer or early autumn for harvest the following spring, are important new alternative crops in the Willamette Valley. These crops offer a source of cash flow in the spring, present the opportunity for three crops in two years, and may be less expensive to grow because of reduced needs for insecticides and irrigation. Cauliflower, onions, and spinach have shown the most promise as overwintered crops.