A Bridgehampton silt loam which had received various amounts of potassium fertilizers for 44 years was analyzed for extractable or exchangeable K by 6 methods. Total K and that removed by boiling IN HNO 3 were also deter mined. The methods measured significantly different quantities of K. The PeechEnglish method extracted more than did the North Carolina, Maine, or Morgan pro cedures. Neutral normal ammonium acetate extraction and a method employing IR120 resin (Amberlite) were inter mediate. The use of exchange resin, although too lengthy for rapid soil testing, appeared more effective in estimat ing crop response (mixed hay yields 195455) than did the buffered acetate solutions. The North Carolina acid
A study was made in cylinders to measure the effect of incorporating 10 tons of pine and oak chips per acre to a Merrimac sandy loam. The influence of such factors as level of nitrate nitrogen, soil reaction, and size of wood chips, were investigated.Using nitrate nitrogen depression as a measure of rate of decomposition, it was found that oak chips decomposed more rapidly than pine chips. This was supported by annual sieving experiments. These measurements showed significantly less oak chips remaining at the end of 12 and 24 months than pine chips.Although 55 to 85% of the wood chips decomposed, organic matter accumulation proved to be meager. No significant differences due to treatments were found. There was some indication that soils at pH 5.0-5.5 accumulated somewhat greater amounts of organic matter than those at pH 6.0-6.5.The relationship between carbon, as determined by the chromic acid titration method, and total carbon, did not change appreciably after 2 years of wood chips decomposition. There was no significant difference in the amount of chromic acid oxidizable carbon due to treatment.The effect of various treatments upon total soil nitrogen was small. No constant relationship could be found, in spite of wide differences in the amount of soluble nitrogen added to the soils. Although the carbon-nitrogen ratios of the soils generally widened, increases were small. Soil reaction did not change appreciably due to additions of wood chips. Ammonia accumulations were negligible.After 2 years of decomposition, 150 pounds of nitrogen gave highly significant increases in the yields of beets and spinach. Wood chip residues did not depress plant growth. Small chips resulted in significantly higher yields than treatments containing large chips.An auxiliary study showed that 100 and 150 pounds of nitrate nitrogen added to beets and spinach, respectively, overcame any depressing effect of additions of 10 tons of small pine chips. With low available nitrogen, wood chips depressed the growth of beets and spinach. This was not true after 12 months of decomposition.
Beneficial effects of redtop residues on yields of potatoes grown on a Bridgehampton silt loam were correlated with increased soil aggregation; particularly with larger ag gregates. There was an accumulation of carbon in all aggregates studied. However, the quantity does not appear to be related consistently to degree of aggregation. Analy ses of total soil and aggregates (> 1 mm., 1 to 0.25 mm., 0.25 to 1 mm.) for microbial gums, polyuronides and acid hydrolyzable polyhexose carbohydrates indicate a simi larity in quantities of these constituents as functions of organic carbon. Generally, somewhat wider C/N ratios (13:1) were found in larger aggregates where redtop was included, compared with smaller sizes (11:1). Extraction of organic matter with 0.5IV NaOH and neutral 0.1M pyrophosphate indicates similar humic materials loosely held by this silt soil regardless of source. About 6 to 9% of the total carbon found in aggregates could be con sistently accounted for as acidhydrolyzable carbohydrate. There was little difference in this fraction due to rotation or size of aggregate.
Waste grain and vegetative material (stems and leaves) collected from a maize field several months after harvest was analysed by bi-dimensional thin layer chromatography for the presence of aflatoxins, deoxynivalenol, ochratoxin A, sterigmatocystin, T-2 toxin and zearalenone. Deoxinivalenol (0.7 mg/kg) and T-2 toxin (4.1 mg/kg) were found in the grain and zearalenone (3.0 mg/ kg) was found in the stem and leaf. No other toxins were detected. The stubble was examined for the presence of potentially toxigenic Fusarium species, and F. poae, F. moniliforme var. subglutinans and F. crookwellense were isolated and identified. When these isolates were cultured on cracked corn, only F. crookwellense was found to produce micotoxins and then only zearalenone was detected. As corn stubble is commonly grazed in Argentina and in other countries, these findings identify a further source of mycotoxins that may adversely affect animal health and productivity.
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