For no‐tillage maize (Zea mays L.) planted in sod, production usually involves the use of a contact herbicide to chemically mow or kill the grass sod. Such a procedure often necessitates costly forage reestablishment and subjects the land to water and wind erosion hazards during noncrop periods. Substantial acreage of rolling, erosive land presently is being row cropped. Field studies on different soil types were designed to investigate: a) the feasibility of chemically suppressing the grass sod for maize production; b) maintaining a sod cover for erosion control; c) providing sufficient forage for fall and winter animal grazing. More than 20 treatments involving growth retardants and sublethal herbicide rates were evaluated for maize production in tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) sods at two southern Illinois locations from 1975 to 1977. The growth retardants which resulted in the best combination of maize yield and grass production in these experiments were maleic hydrazide (1,2‐dihydro‐3,6‐pyridazinedione), fluridamid (N‐[3‐[1,1,1‐trifluoro methylsulfonyl) amino]‐4 methylphenyl]acetamide), and mefluidide (N‐[2,4‐dimethyl‐5[[(trifluoromethyl) sulfonyl]amino]phenyl] acetamide. The herbicides which most nearly met experimental objectives were glyphosate (N‐(phosphonomethyl)glycine), glyphosate plus atrazine (2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine), metolachlor (2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl) acetamide), metolachlor plus atrazine, and dalapon (2,2‐dichloropropionic acid). In most instances, it was necessary to apply a band of paraquat (1,1′‐dimethyl‐4,4′‐bipyridiniumion) over each row for acceptable maize yield. In these experiments, it was possible to obtain good maize yields while maintaining at least 50% of the grass sod with little or no erosion observed. This method offers the potential for a combination of maize production and grazing on erosive land.

Published results of Rhizobium research studies are often conflicting and inconclusive as to whether soybean [Glycine max (L.) Merr.] inoculation is beneficial in soils previously cropped to soybeans. Greenhouse studies were conducted to clarify the effect of previous soybean cropping histories (soybeans grown 0 to 11 years previously or never) on soybean nodulation and growth responses and Rhizobium japonicum serogroups and population in southern Illinois soils. Sterile soybean seeds were inoculated with the supernatant from soil suspensions representing different soybean cropping frequencies and variable years since the last soybean crop. Seeds were planted in pots of sterilized sand in the greenhouse and soybean growth, nodulation, and nodule mass or dry weight were evaluated. Dominant nodule serogroup determinations were made on selected treatments. Relative N2 fixation was estimated by means of an acetylene‐reduction assay (ethylene production) and MPN determinations were made on cropping history samples in one experiment. Correlations were not significant between soybean cropping frequency and nodule number, nodule mass, or ethylene production with but one exception. In most instances, the soybean cropping history of the soils used to inoculate seed did not influence soybean top or root growth if soybeans had ever been grown on a field. No aspect of soybean cropping history significantly influenced the predominant serogroups present in soybean nodules. These results indicate that under the conditions of these experiments sufficient populations of Rhizobium japonicum persist in southern Illinois soils for at least 10 or 11 years, resulting in good soybean nodulation and growth. Based on these studies, the recommendation of inoculating soybean seed before planting for “inexpensive insurance” regardless of soybean cropping history is questionable.

Growth control of grass and other vegetation has been achieved on a limited scale by the use of chemical retardants on highway roadbanks and similar rough turfgrass areas. A few chemical growth retardants are available commercially and a number of experimental chemicals have been developed recently. Five greenhouse experiments and four field studies were conducted from 1970 to 1972 at Southern Illinois University to evaluate commercial and experimental chemical retardants on ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.), one of the leading grasses used in Illinois for roadbank stabilization. Nineteen chemicals or formulations were tested with potted tall fescue in the greenhouse and several rates of eight different chemicals were evaluated under field conditions. On selected dates after treatment, grass plots were evaluated as to height, color maintenance, stand losses, and weed infestations. In greenhouse trials the most promising results were obtained with Slo‐Gro, a maleic hydrazide (MH) formulation [diethanolamine salt of 6‐hydroxy‐3‐(2H)‐pyridazinone]; MON‐820 (N‐phosphonomethylimino‐diacetic acid); MON‐845 [N,N‐Bis(phosphonomethyl)glycine]; MBR‐6033 (3‐trifluoromethyl‐ sulfonamido‐p‐acetotoluidide); and Maintain CF‐125 (methyl‐2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate, methyl‐9‐hydroxyfluorene‐9‐carboxylate, methyl‐2, 7 dichloro‐9‐hydroxyfiuorene‐9‐carboxylate). MBR‐6033 showed considerable potential in providing balanced control of growth while enhancing or maintaining a desirable green color. Sustaining color was difficult with other chemicals evaluated when used at rates sufficient to reduce growth over a long time interval. MON‐820, MON‐845, Slo‐Gro (MH), and Maintain CF‐125 reduced grass growth and dry matter yield markedly at selected rates in field studies. However, color deterioration, stand reduction, and weed infestation were serious at higher chemical rates. MON‐814 (ethanolamine‐p‐nitrobenzene‐sulfonylurea), MON‐139 (phosphonomethylglycine, isopropyl‐ammonium salt), and MON‐464 (phosphonomethylglycine, calcium salt) were less consistent in reducing growth while sustaining color. Slo‐Gro, MBR‐6033, and Maintain CF‐125 effectively suppressed tall fescue seedhead development. Information gained from these studies indicates that treatment with selected commercial and experimental growth retardant chemicals can result in effective tall fescue growth control and seedhead suppression. In some instances, chemical treatment of grass resulted in some degree of phytotoxicity and grass color losses. A notable exception was treatment with MBR‐6033 (Sustar), which gave good growth control while maintaining or enhancing grass color.

No abstract

A soil solution displacement method was used to evaluate the effect of CaCO3 on soil retention of sulfate. A decreased amount of sulfate retention was noted with increased rates of CaCO3.By means of a split‐root technique, plants of soybeans (Clycine max (L.) Merrill) and cotton (Gossypium hirsutum L.) were grown in a Dothan subsoil which contained a large amount of adsorbed sulfate, and to which had been added several rates of CaCO3. As CaCO3 rate was increased the uptake of sulfate by five crops of soybeans and one crop of cotton grown successively in the same soil was generally greater. A portion of the adsorbed sulfate in the untreated soil was available, but available sulfate became limiting for the third crop of soybeans and for all successive crops of soybeans and cotton.