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Potato (Solanum tuberosum L.) is the fourth most important food crop in the world after corn, wheat, and rice. It is adapted to a wide range of growing conditions, producing high yields with a near-optimum balance of nutrients for human consumption. China is the world's largest potato producer and continues to account for a large part of the global increase in potato production. Although the potato can be highly productive, it has a relatively shallow root system and often requires significant nutrient inputs to maintain tuber productivity and quality. Each metric ton of tubers removes approximately 3.8 kg nitrogen (N), 0.6 kg phosphorus (P), and 4.4 kg potassium (K). Proper nutrient management, therefore, is extremely important for sustaining high tuber yield and quality. Lack of adequate balanced fertilization in China is reportedly a yield-limiting factor in some areas. For example, potassium (K) is very important for producing a potato crop with high tuber yield and quality. Limited K resources in China and continued cropping have resulted in below-adequate levels of soil K in many regions of the country, which will impact potato production. On the other hand, based on U.S. experience, the high nutrient demand by potato, application of high rates of fertilizer, and production on coarser textured soils can result in nutrient losses. Nutrient best-management practices are developed with the objective of optimizing production, net returns, and minimizing environmental degradation. In general, optimal N management has had the most important impact on tuber yield and quality compared with the other essential elements. Best management practices for N fertilization include appropriate selection of rate, source, timing, and method of application. Optimal management of irrigation is also important to improve N-uptake efficiency and minimize N losses while maintaining high yields and quality. Phosphorus is another key nutrient important from both production and environmental standpoints. Adequate P is required for optimum tuber-set, while excessive rates may result in soil-P buildup and potential runoff problems. This review will focus on various management techniques to maximize nutrient-uptake efficiency by potatoes. [ABSTRACT FROM AUTHOR]

During the incineration of turkey manure, a wide variety and concentration of nutrients are conserved in the turkey manure ash (TMA). In particular, the high concentration of citrate-soluble phosphorus (P) (43 g kg-1) may make it a suitable P source for crop production. The ash is alkaline with a pH of 12.2. We conducted a soil incubation study using a low-P soil with a pH of 6.2 to evaluate the effects of TMA on soil pH and extractable P. Two TMA rates, based on citrate-soluble P (10.9 and 21.9 mg kg-1), were compared with equivalent rates of triple superphosphate (TSP). In addition, a 0-P control was included. At the rates tested, TMA slightly increased soil pH, but this increase would be of minor agronomic importance. At equivalent P rates, changes in water-soluble P (WSP) concentrations with TMA and TSP were similar. Changes in iron-oxide-strip-extractable P (FeO P) and Bray 1 P concentrations were greater with TMA than with TSP. In contrast, changes in Olsen P concentrations were greater with TSP than with TMA for up to 32 days. For TMA, the ability of the tests to extract P was ranked, from highest to lowest, as Bray 1 P > FeO P > Olsen P > WSP, and for TSP they were ranked Bray 1 P ≥ Olsen P ≥ FeO P > WSP. However, the Bray 1 P and FeO P tests tended to overestimate plant-available P because they measured more citrate-soluble P than that added with TMA. We conclude that TMA can be used as a P source for crop production and that the Olsen test may provide a better estimate of plant-available P in TMA-amended soil. [ABSTRACT FROM AUTHOR]

Incinerating turkey manure is a new option in the USA to generate renewable energy and to eliminate environmental problems associated with manure stockpiling. Incineration produces turkey manure ash (TMA) with a nutrient content of 43 g phosphorus (P) kg-1 and 100 g potassium (K) kg-1. We conducted a greenhouse pot study using a low P (6 mg kg-1) and high K (121 mg kg-1) soil/sand mixture with a 7.0 pH to evaluate early growth response of corn (Zea mays L.) to TMA. A control and five rates based on P (5.6, 10.9, 16.5, 21.9, and 27.2 mg kg-1) and respective K contents in TMA were compared with triple-superphosphate and potassium chloride fertilizer. Plant height and stalk thickness at 24 and 31 days after emergence (DAE) were greatest with the fertilizer, but no differences were detected at the final sampling (52 DAE). Regardless of nutrient source, plant biomass increased with P rate. Because of faster initial plant development, corn dry matter 52 DAE was 15 to 20% greater with fertilizer than with TMA. Corn tissue P concentration was greater with TMA than with fertilizer, but P uptake was similar. Tissue micronutrient concentrations were greatest for the control. Bray 1 P appeared to extract excessive amounts of P in TMA-amended soil, whereas soil P levels with the Olsen extractant provided an estimate of plant-available P that was consistent with plant response. Based on this first approximation, we conclude that TMA is a potential source of P for field crops. Field studies are required to determine recommended application rates. [ABSTRACT FROM AUTHOR]

A power plant that utilizes turkey manure as fuel to produce energy was built in Benson, Minnesota, and started full energy production in 2007. The plant was built to meet legislative requirements governing the use of renewable sources to generate energy in Minnesota. Although the use of turkey manure as biofuel generates energy, it also results in turkey manure ash (TMA) as a by-product that contains phosphorus (P), potassium (K), sulfur (S), and zinc (Z) as well as other essential and nonessential elements. A 2-year study was conducted to compare TMA with triple-superphosphate and potassium chloride fertilizers as a source of nutrients for alfalfa (Medicago sativa) at three locations: Lamberton, Morris, and Appleton, Minnesota. The soils at Lamberton and Appleton were acidic with P and K concentrations ranging from medium-high to very high, whereas the soil at Morris was alkaline with high concentrations of P and K. The experiment consisted of a control (0 P and 0 K) and annual and split applications of TMA and fertilizer. Annual TMA and fertilizer rates were 84 kg P2O5 ha-1, 118 kg K2O ha-1, and 34 kg S ha-1. Split rates were 42/42 kg P2O5 ha-1, 59/59 kg K2O ha-1, and 17/17 kg S ha-1. However, because of an overestimation of citrate-soluble P in 2005 for the TMA, the total amount of available P applied with the TMA for the 2-year study was 168 kg P2O5 ha-1 compared with 286 kg P2O5 ha-1 for the fertilizer. In the first year, fertilizer resulted in greater alfalfa biomass yield than TMA and the control, whereas in the second year, alfalfa yields with TMA and fertilizer were similar and both more than the control. In 2005, TMA resulted in more copper (Cu) and S tissue concentrations than the fertilizer. In 2006, application of both sources increased tissue P and S concentrations compared with the control. The TMA increased tissue Cu concentration and Zn plant uptake compared with fertilizer. Bray P1-extractable soil P concentrations were less with TMA and control treatments than with the fertilizer treatments. Ammonium acetate-extractable soil sodium (Na) concentrations were greater with TMA than with fertilizer and the control. By the second year, both ash and fertilizer treatments resulted in more K uptake than the untreated control with no difference in K uptake between the two sources or time of application. Both sources were effective in increasing P uptake compared with the untreated control. TMA was shown to be an effective source of nutrients for alfalfa production. [ABSTRACT FROM AUTHOR]

‘Honeycrisp’ is a recently released cultivar of apple ( Malus x domestica ) developed by the University of Minnesota, now in high demand by growers and consumers. This cultivar is susceptible to bitter pit, especially when the trees are young and the fruit load is low. The effects of calcium (Ca) sprays, fruit thinning, vegetative growth, fruit and leaf nutrient concentration on bitter pit incidence, and two sampling methods for nutrient analysis were studied. Bitter pit incidence was associated with several variables, including Ca and phosphorus (P) concentrations in leaves and fruits, magnesium (Mg) concentration in leaves, and yield parameters. Fruit Ca concentration and content for the growing season were modeled, which allowed the determinations of Ca levels associated with bitter pit incidence. Our data suggest that plug analysis was less sensitive than fruit-segment analysis for finding differences in Ca concentrations. [ABSTRACT FROM AUTHOR]

Application of sugar beet processing by-products to agricultural land has become a common practice to reduce disposal costs. This study was conducted to estimate N mineralization in soils amended with sugar beet processing by-products. Field moist Bearden and Angus soils adjusted to 80% field capacity water content and amended with beet pulp, beet tailings, spoiled and fresh sugar beet roots or biosolids (standard) were incubated at 30°C for 120 days. A non-amended control was also included. Periodically, soil samples were removed and analyzed for mineral nitrogen (N) (NH[sup +, sub 4]-N + NO[sup -, sub 3]-N). Addition of sugar beet byproducts resulted in N immobilization before the start of net N mineralization for both soils. In contrast the biosolids showed net N mineralization over the entire incubation period. The data on N immobilization and mineralization were fitted by a double exponential model. This model allowed the estimation of both potential N mineralization and potential N immobilization kinetics of sugar beet waste amended soils. The maximum amount of N immobilized varied from 25.6 to 60.3 and from 34.0 to 121.6 mg kg[sup -1] soil, respectively, for Bearden and Angus soils. Expressed as a percentage of total N added, the N mineralized (% availability index) varied from 0 to 17.3% for various sugar beet processing by-products in the two soils. The effect of different sized spoiled sugar beet pieces on N mineralization showed that as size decreased, N immobilization increased and N availability decreased. [ABSTRACT FROM AUTHOR]

Describes the development of aquaculture into a technology. Reason for the interest in aquatic animals as food; Manner in which aquaculture offers the possibility of optimizing the use of biological energy by man; Information on fish farming around the world.

Portable electrodes for rapid quantitative determination of nitrate‐N (NO3‐N) in plant sap have recently been developed, thus enabling a quick assessment of the crop nitrogen (N) status. The intent of this study was to provide diagnostic criteria necessary for the interpretation of petiole sap NO3‐N concentrations for potato (Solanum tuberosum L.). Specific objectives were to characterize the relationship between potato petiole sap NO3‐N concentration and petiole NO3‐N determined by conventional dry weight analysis, and to establish NO3‐N sufficiency ranges (NSR) for irrigated potatoes based on sap analyses associated with maximum and 85–95% of maximum yield. A four‐year experiment was conducted on a loamy sand soil (Udic haploboroll) at the Sand Plain Research Farm, Becker, Minn. Ten treatments consisting of various rates and times of N application were evaluated. Recently matured leaves were collected every 10 to 14 days, and petioles were split for sap NO3 and dry tissue NO3 analysis. Two portable NO3 electrodes, the Cardy and Hach meters, designed for quick tests, and a fixed laboratory method, the Wescan, were used to determine sap NO3‐N concentrations. Dry petiole NO3‐N and petiole sap NO3‐N were linearly and significantly related, with regression coefficients r2=0.91, 0.92, and 0.93 for the Cardy, Hach, and Wescan methods, respectively. Nitrate‐N sufficiency ranges determined with the Cardy were 50 mg L‐1 higher than those determined with the Hach. During the vegetative/tuber initiation stage (15–30 days after emergence), NSR were 1350–1450, and 1300–1400 mg L‐1 for the Cardy and Hach, respectively. As the season progressed, the NSR decreased. During the tuber bulking period (30–75 days after emergence), NSR were 600–1350 mg L‐1 for the Cardy and 550–1300 mg L‐1 for the Hach. At maturity, NSR were less than 600 and 550 mg L‐1 for the same respective electrodes. Petiole sap NO3‐N determined by either the Cardy or Hach methods can be a quick and useful tool to assess potato N status. [ABSTRACT FROM PUBLISHER]

Incineration reduces sewage sludge volume, but management of the resulting ash is an important environmental concern. A laboratory incubation study and greenhouse pot experiments with lettuce (Lactuca sativa L.) and corn (Zea mays L.) were conducted to examine the potential for recycling elements in sewage sludge incinerator ash in agricultural systems. Ash rates in both the laboratory and greenhouse were 0, 0.95, 3.8, 15.2, and 61.0 g/kg soil (Typic Hapludoll). Ash was also compared to equivalent rates of citrate soluble P from superphosphate fertilizer in a soil‐less growth medium. During soil: ash incubation, Olsen P and DTPA extractable copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) increased with incubation time at the higher ash rates. Release rates diminished rapidly, however, and the limited release of these elements after 280 days was associated with decreasing pH. In the greenhouse, ash amendment increased extractable soil P, plant tissue P, and the growth of lettuce and corn. Ash was a less effective P source than superphosphate fertilizer in the soil‐less growth medium and Olsen P levels were more consistent with these differences than Bray P. Ash increased extractable soil levels and plant tissue concentrations of calcium (Ca), magnesium (Mg), sodium (Na), Cu, and Zn, but extractable soil manganese (Mn) and plant tissue Mn decreased. Ash increased soil pH and extractable SO4‐S. DTPA extractable Cd and Pb increased, but chromium (Cr) and nickel (Ni) decreased. Lettuce accumulated higher amounts of these trace metals than corn, but tissue concentrations were at control levels or below detection limits in both crops. [ABSTRACT FROM PUBLISHER]