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Poultry litter when applied to agriculture lands contains high trace element concentrations that may become toxic to plants and pose a risk to surface water and groundwater. We evaluated whole soil elemental concentrations throughout the soil profile using the US Environmental Protection Agency digestion method 3052 for Alabama benchmark soils that had received more than 20 years of poultry litter. Paired soils that had not received poultry litter were equivalently characterized. Pairwise comparison tests indicate that trace element concentrations were significantly greater (P< 0.05) in poultry litter–amended soils than those in nonamended soils. Cadmium, As, Cu, Ni, and Cr concentrations significantly increased with soil profile depth relative to those in nonamended soils. Chromium concentration significantly increased from 38.8 mg kg−1(0–15 cm) to 116 mg kg−1(75–90 cm) in Malbis soil. The downward migration of these metals and metalloids may pose a risk to shallow groundwater resources and, if the soil is eroded, may pose a risk to surface water resources.

Because sweetpotato [Ipomoea batatas (L.) Lam.] stem cuttings regenerate very easily and quickly, a study of their early growth and development in microgravity could be useful to an understanding of morphological changes that might occur under such conditions for crops that are propagated vegetatively. An experiment was conducted aboard a U.S. Space Shuttle to investigate the impact of microgravity on root growth, distribution of amyloplasts in the root cells, and on the concentration of soluble sugars and starch in the stems of sweetpotatoes. Twelve stem cuttings of 'Whatley/Loretan' sweetpotato (5 cm long) with three to four nodes were grown in each of two plant growth units filled with a nutrient agarose medium impregnated with a half-strength Hoagland solution. One plant growth unit was flown on Space Shuttle Colombia for 5 days, whereas the other remained on the ground as a control. The cuttings were received within 2 h postflight and, along with ground controls, processed in ≈45 min. Adventitious roots were counted, measured, and fixed for electron microscopy and stems frozen for starch and sugar assays. Air samples were collected from the headspace of each plant growth unit for postflight determination of carbon dioxide, oxygen, and ethylene levels. All stem cuttings produced adventitious roots and growth was quite vigorous in both ground-based and flight samples and, except for a slight browning of some root tips in the flight samples, all stem cuttings appeared normal. The roots on the flight cuttings tended to grow in random directions. Also, stem cuttings grown in microgravity had more roots and greater total root length than ground-based controls. Amyloplasts in root cap cells of ground-based controls were evenly sedimented toward one end compared with a more random distribution in the flight samples. The concentration of soluble sugars, glucose, fructose, and sucrose and total starch concentration were all substantially greater in the stems of flight samples than those found in the ground-based samples. Carbon dioxide levels were 50% greater and oxygen marginally lower in the flight plants, whereas ethylene levels were similar and averaged less than 10 nL·L-1. Despite the greater accumulation of carbohydrates in the stems, and greater root growth in the flight cuttings, overall results showed minimal differences in cell development between space flight and ground-based tissues. This suggests that the space flight environment did not adversely impact sweetpotato metabolism and that vegetative cuttings should be an acceptable approach for propagating sweetpotato plants for space applications. [ABSTRACT FROM AUTHOR]

Sweet potato [Ipomoea batatas(L.) Lam] is being grown with the nutrient film technique as part of the National Aeronautics and Space Administration's Controlled Ecological Life Support System (CELSS) program for long‐termed manned space missions. Our objective was to evaluated the effects of two levels of photosynthetic photon flux (480 and 960 μmols m−2s−1PPF) and three N/K ratios (1:1.1, 1:2.4, and 1:3.6) on yield of sweetpotato when grown using this technique. Vine cuttings (15‐cm length) of ‘Georgia Jet’ and T1‐155 were grown in each treatment for 90 or 120d, respectively, in controlled‐environment growth chambers. Storage root growth for Georgia Jet and T1‐155 increased with light intensity, while foliage growth decreased with high K levels. The number of storage roots produced by each plant increased with intensity only for Georgia Jet but was not significantly influenced by higher K levels for either cultivar. Light by N/K interactions were not significant. The level of PPF exerted a greater effect in enhancing sweetpotato storage root yield in nutrient film than did N/K ratio.