Summary Rooted-cuttings and saplings of green ash (Fraxinus lanceolata) and hybrid poplar (Populus spp) were planted on a former municipal refuse landfill and on a nearby nonlandfill control plot. The root systems of four trees of each species and size were excavated on the landfill plot -two growing in an area where the concentrations of anaerobic landfill gases were relatively high and two in a relatively low-gas area. Two trees of each species and size were also excavated on the control. The root systems of both species were significantly shallower on the landfill plot than on the control. Green ash appeared to avoid the adverse gas environment of the deeper soil layers on the landfill by producing adventitious roots. Hybrid poplar became adapted in a different manner, by redirecting root growth from the deepter soil layers to the soil surface.

Gleditsia triacanthos var. inermis seedlings were field planted in compacted and non-compacted soil in both normal oxygen and reduced oxygen soil atmosphere. Entire root systems were excavated and mapped. Compaction caused significantly shallower roots in normal and reduced oxygen areas. Roots in the reduced oxygen area were not significantly shallower than in normal oxygen areas. Root spread was correlated with stem diameter and branch spread. Lateral roots extended three times as far from the trunk as did the branches.

No abstract

No abstract

The roots of tomato plants were fumigated with simulated refuse-generated gas mixtures at levels of methane (CH 4 ), carbon dioxide (CO 2 ), and oxygen (O 2 ) previously measured in the atmospheres of landfill cover soils associated with poor growth or death of plants (5). A concentration of 18% CO 2 or greater, exceeded in almost 30% of thirty-two landfills examined throughout the United States, caused reduced growth and visible symptoms on tomato after 1 wk, regardless of O 2 level. Doubling the CO 2 level to that encountered in a typical local site (Edgeboro Landfill) resulted in more severe symptom development and the

No abstract

Lycopersicon esculentum (tomato) plants were grown in were harvested immediately and/or 48 hr after fumigation. sand culture under two different levels of nitrogen nutrition Tissue analyses (Kjeldhal method) indicated that total N (28 mg/liter N0 3-N and 140 mg/liter N0 3-N) supplied in content had increased following exposure to NO 2 , Hoagland's solution. One month after being transplanted, particularly in the leaves of the 140 mg/liter N0 3-N one group of plants was fumigated either with 0.47 mg/m 3 treatment, as had fresh and dry weights. No NO 2 injury was NO 2 for 80 hr or with 0.76 mg/m 3 for 164 hr and a second apparent on any of the fumigated plants. group received charcoal-filtered air. The stems and/or leaves

No abstract