Fertilizer Recommendations

A soil test is the most accurate guide to fertilizer requirements. Good management practices are essential if optimum fertilizer responses are to be realized. These practices include use of recommended varieties, selection of adapted soils, weed control, disease and insect control, good seed bed preparation, proper seeding methods, and timely harvest.

Because of the influence of soil type, climatic conditions, and other cultural practices, crop responses from fertilizer may not always by accurately predicted. Soil test results, field experience, and knowledge of specific crop requirements help determine the nutrients needed and the rate of application.

Fertilizer applications for carrots should insure adequate levels of all nutrients. Optimum fertilization is intended to produce top quality and yield commensurate with maximum returns.

The following are recommendations for нted. If banding equipment is available, some of the fertilizer can be applied at planting. The suggested fertilizer applications are based on a 24" row spacing and 20-25 plants per linear foot of row.

Recommended soil sampling procedures should be followed in order to estimate fertilizer needs.

Nitrogen (N)

Because of the mobility of nitrate in soils and the complex transformations from organic matter, soil tests for nitrogen are not reliable for predicting nitrogen fertilizer needs in the eastern half of Minnesota (Area 1), particularly on sandy irrigated soils. Therefore, Nitrogen recommendations are based on yield goal, previous crop, and soil organic matter content.

UNIT II.

ONIONS

Text 1. Variety Types.

Bulbing onion varieties are classified according to day length. All bulb onions grown in the Minnesota are classified as long-day varieties requiring 14 or more hours of day length before bulbing is initiated. Technically, all onions are "long-day" plants, in that bulbing begins as day length increases. Short-day varieties are those requiring only 10 to 12 hours of day length for bulbing to occur. These are grown in southern states generally below the 35 th. parallel, and are not suitable for bulb production in the midwest, except as pearl or boiler varieties, or for over-winter production.

Temperature and light intensity and quality can modify the onion bulbing response. High temperatures and bright days can "compensate" for some day length, causing onions to bulb sooner than they would otherwise. Overcast, cool temperatures, delay bulbing. Time of bulbing is an important factor in determining onion bulb size. Early bulbing contributes to small bulb size, with delayed bulbing resulting in larger size.

Uniformity of maturity (rate of foliage collapse) is very important in bulb size uniformity and storage quality. Foliage collapse in hybrid varieties tends to occur over a period of three to four days, with close to 100% of the tops falling, however in non-uniform (often open-pollinated) varieties, this could occur over a period of several weeks with a percentage of the tops not falling at harvest. In such varieties, bulbs with early tops-down contribute to incidence of bald onions (skinless) at harvest, while those whose tops resist falling do not cure properly, contributing to decay in storage.

Cool temperatures and late plantings predispose varieties to bull (thick) necks, a trait that contributes to poor storability due to post-harvest disease infection. This is especially true of late varieties that may have poor bulbing uniformity qualities (sometimes more prevalent in open- pollinated varieties).

Selecting the correct variety for your production area and understanding the climatic and other environmental factors that effect its performance is extremely important.

Yields of the same variety will vary from year to year depending on weather conditions, planting schedules and soil types. Many varieties are available and new releases occur each year.