Browsing Research Progress Reports by Author "Walworth, James L."
The Effect of Hilling on Yield and Quality of PotatoesCarling, Don E.; Walworth, James L. (Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, 1990-06)Traditionally, commercially grown potatoes are hilled in the production cycle between emergence and closure of the canopy. Hilling is usually accomplished with disks, sweep shovels, or similar tools that lift soil from between rows and deposit it beside and on top of the row. Reasons for hilling may include: improved weed control, improved drainage, minimization of greening of tubers, and raising of soil temperatures. Proper management of each of these factors may result in an increase in quality and quantity of tuber yield. Negative aspects of hilling have also been noted. Saffigna et al. (1976) reported that water distribution was uneven under potato hills, resulting in uneven availability of water to plants and increased loss of fertilizer due to leaching. Hilling operations may also damage potato plants, and significant reductions in yield are known to result from hilling and other types of cultivation (Nelson and Giles, 1986). Many commercial growers wait until vines are 12 or more inches tall before hilling. This scheduling is preferred because at this time the danger of covering plants is minimal. However, the vines of larger plants may sustain greater damage from hilling than smaller plants. Also, the possibility of damaging roots and stolons increases as the plants increase in size, so there may be advantages to hilling when plants are younger and smaller. Four different treatments including variations in time of hilling and height of hill were compared with no-hilling on four varieties of potato in the 1988 and 1989 growing seasons. This report contains a preliminary summary of data collected from these studies.
Effects of Potassium Source and Secondary Nutrients on Potato Yield and Quality in Southcentral Alaska.Walworth, James L.; Gavlak, Raymond G.; Muniz, June E. (School of Agriculture and Land Resources Management, Agricultural and Forestry Experiment Station, 1990-12)Calcium (Ca), magnesium (Mg), and sulfur (S) are required for the growth and development of all higher plants. They are commonly referred to as secondary nutrients because they are less often limiting to plant growth than the primary nutrients nitrogen (N), phosphorus (P), and potassium (K), although secondary nutrients are as critical for crop growth and development as the primary nutrients. There is limited information available concerning secondary nutrient requirements of potatoes grown in southcentral Alaska. Laughlin (1966) conducted studies between 1961 and 1963 comparing potassium chloride (KCl) and potassium sulfate (K2SO4) as potassium sources for Green Mountain potatoes, and determined the effects of varying rates of magnesium sulfate (MgSO4) and K2SO4 on Kennebec potatoes. Since these studies were conducted without irrigation and at production levels about one-half those obtained by top producers in the Matanuska Valley today, it was considered appropriate to expand upon the previous work using current production practices. Potassium was supplied as KCl and K2 SO4 to explore the need for additional S under local potato production conditions and to determine the effects of the chloride (Cl) and sulfate (SO4) anions on production and quality of potato tubers. In addition, Mg and Ca were added to determine whether the background levels of these nutrients were adequate for optimum production.
Effects of Soil Fertility on Potato Plant Development in the Matanuska ValleyWalworth, James L.; Gavlak, Raymond G.; Muniz, June E. (Agricultural and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska Fairbanks, 1990-06)Nutrient uptake and physiological development in potato plants have been investigated in major potato growing regions, but comparable studies have not been conducted in high latitude areas such as the potato producing sections of southcentral Alaska. Knowledge of plant development and nutrient partitioning among various plant parts is important both in terms of general understanding of the growth habits of potatoes in a unique environment and for improved management of field production of this crop. Nutrient response data provide a basis for fertilizer application recommendations. A field study designed to define potato plant development under various fertility regimes was initiated in 1989. Potato plants were intensively sampled through the growing season to determine the effects of nutrient availability on growth processes, to measure growth rates of various plant parts, and to determine the fate of nutrients absorbed by the plant. The results of the effects of soil fertility on potato plant development are presented in this report. Nutrient uptake and partitioning data will be compiled in later publications when laboratory analyses are complete.