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The most common de-icing material applied by the Massachusetts state highway department is sodium chloride (NaCl). In Massachusetts, the rate of application of de-icing agents is about 240 lb (110 kg) of sand and 12 lb (5.5 kg) of NaCl per lane mile (1.6 km). The objective of this research was to examine injury to plants along roadsides and to assess relationships of damage to the amount of Na detected in plants and soils. The damage on most plant species was manifested as burning or browning of the leaves or needles. Coniferous species, especially pines (Pinus spp.), were sensitive to NaCl injury. In coniferous species, the damage appeared as browning on the ends of the needles, but new growth was not affected. Most of the damage occurred on the needles on the tree side that faced the road and where salt spray from cars or plows could have been a factor in the degree of damage. Widespread damage was also seen on spruce (Picea spp.), sumac (Rhus typhina), and mountain laurel (Kalmia latifolia) along roadsides. With sumac, injured plants had only 67 ORDER REPRINTS 10% of the foliage as uninjured plants. Some salt-tolerant species, apparently undamaged by NaCl, in the same vicinity as the damaged plants, were various oaks (Quercus spp.), maples (Acer spp.), grasses (mixed species), ferns (mixed species), and yarrow (Achillea millefolium). The Na concentrations in the leaves of pines, sumacs, grasses, and oaks decreased as the distance from the road increased. The Na concentrations in pine needles were 3356 mg kg 21 at 10 feet, 1978 at 15 feet, and 1513 mg kg 21 at 20 feet. The Na concentrations in maple leaves decreased with the Na concentrations being 249 mg kg 21 at 10 feet and falling to 150 mg kg 21 at 30 feet. The concentrations of Na in roadside soil ranged from 101 mg kg 21 at 5 feet to 16 mg kg 21 at 30 feet from the roadside, with a marked decrease in the Na concentration in the soil after 15 feet. The pH decreased as the distance from the road increased ranging from 7.60 at 5 feet to 5.78 at 30 feet. The electrical conductivity values decreased as the distance from the road increased and ranged from 0.16 dS m 21 at 5 feet to 0.12 dS m 21 at 30 feet. This study suggests a relationship between Na accumulation, in leaves and in soil, and injury to roadside plants.

Integrating cover crops into farming systems may contribute to meeting N demands of succeeding crops and therefore decrease fertilization and environmental concerns. To study the trend of released N in buried (BR) and surface residues (SR) of three different cover crops a 2‐yr field experiment was conducted in a randomized complete block design on a fine sandy loam. Forage radish (Raphanus sativus L.) and winter pea (Pisum sativum subsp. arvense L.) decomposition rate and N release trend were compared with cereal rye (Secale cereale L.), as the conventionally grown cover crop in Massachusetts, to evaluate if forage radish or winter pea would provide more N for early planted crops in the spring than cereal rye. Forage radish produced the highest dry matter yield (3.46 Mg ha−1) followed by winter pea (3.1 Mg ha−1) and cereal rye (2.42 Mg ha−1). All of the cover crops had a faster residue decomposition and release of N when buried in the soil. Through the decomposition period, forage radish and winter pea lost their initial biomass and N concentration faster than cereal rye in both BR and SR due to higher C/N ratio and lignin concentration in rye. Our results showed a greater potential of forage radish or winter pea for a synchronous N release relative to crop N demands early in the spring than with cereal rye.Core Ideas Forage radish has great potential for synchronous N release with cash crop N demands early in the spring. A high N yielding winterkilled cover crop is preferred over rye if early planting of cash crop is target. Rye may not provide the succeeding crop with sufficient N when terminated early.

Sumnmiiary. Ammonium toxicity resulted in morphological modifications of tomato leaf chloroplasts. The chloroplasts, which are normally flattened around the protoplast periphery, became ellipsoidally rounded and dispersed through the protoplasm. The first apparent effect of plastid degradation was development of many vesicles from the fretwork. Later the grana lamellae swelled, and some disappeared. Eventually, distinct grana could not be detected.Ammonium accumulation, chlorophyll loss, and photosynthetic decrease occurred simultaneously. Initial changes in these processes preceded the detection of modifications of fine structure; however, each continued with further breakdown of the chloroplasts.In many higher plants prolonged application of ammonium as a source of nitrogen leads to serious physiological and morphological -disorders resulting in chlorosis, restricted growth, and in some cases death (4,5,10,29,30 morpho'ogical changes. The symptoms of ammoniumii toxicity suggest that morphological changes mighlt occur in the chloroplasts. Chlorosis of plants treatecl with ammonium has been reported to occur in conjunct.on with an imbalance between the soluble and insoluble nitrogen compounds (4). Chlorophyll synthesis has been shown to be dependent on protesn synthesis (16). Within the leaves of higher plants, the majority of proteins are chloroplastic (19. 35) and exist in a state of turnover. The (proteins of chloroplasts are found in the stroma and in the co;viplex system of lamellar memnbranes of lipoprotein (31). The organization of the lamel]ar network of the chloroplast is dependent on the cellular environment of the leaf (7,14,20,24), particularly the nutrient composition. It was felt that an ultrastructural examination of the clhloroplasts of plants treated with ammonium would provide an indication of the morphological aspects of ammonium toxicity and permit further correlation between morphological features and physiological symptoms of ammonium toxicity. Materials and MethodsTomato plants (Lycopcrsicon escdlenthm Mill., cv. Heinz 1350) were chosen for this study because they deve'op ammloniumn toxicity symptoms rapidly and sequentaliv. Seecds were sown in flats of soil, and the seedlings were grown for 5)weeks in a greenhouse. The vcung plants were then tranisplanted into 8-inch l'astic pots containiing a 1:1 mixture of coarse and f:ne silica sand ancl were treated with Hoagland's.

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