William C. Liebhardt

Potassium is responsible for salinity in soils amended with poultry manure 1

Abstract Soil salinity increases when heavy rates of poultry manure are applied to sandy coastal plain soils. Analysis of soils involved in a poultry manure study during 1970, 1971 and 1972 has shown that soil salinity is primarily associated with a high concentration of ? in the soil solution. Although concentrations of other elements increased with the application of poultry manure also, the increases were not sufficient to account for the salinity in these soils.

Yield of corn as affected by potassium on a coastal plain soil

Abstract Corn (Zea mays L.) yields were determined over a four year period on Kalmia sandy loam soil at Georgetown, Delaware. Yields were not significantly increased by the application of K fertilizer. Potassium soil test level was not significantly correlated with corn yield. Multiple extraction and leaching and changes in soil test K indicated that this soil has a K equilibrium which is reestablished sufficiently rapid to supply K to a growing corn crop.

Fluctuations in soil test values for potassium as influenced by time of sampling

Abstract Soil samples were taken at frequent intervals in 1975 and 1976 from a factorial set of lime ‐K treatments initiated in December 1970 to determine the effect time of sampling has on K soil test values. Previous work at this site had shown wide fluctuations in K soil test values due to sample time thus necessitating a more detailed study than was previously made. Such information is necessary if accurate K fertilizer recommendations are to be made. Samples from 28 unfertilized plots showed that months of sampling significantly affected K soil test values. Soil test values for K were highest in late May and declined as the growing season progressed, remaining low until the relatively higher exchangeable K was re‐established the following spring. Disregard for this phenomenon could result in inaccurate recommendations for K fertilizer.

The arsenic content of corn grain grown on a coastal plain soil amended with poultry manure 1

Abstract The concentration of arsenic in corn grain was not affected by the use of poultry manure from chickens which had been fed 3‐nitro 4‐hydroxy phenyl arsonic acid. Corn was grown on plots receiving in excess of 600 Mt/ha over a three year period which is 10 to 20 times normal use. The results indicate that arsenic is not concentrated in corn grain when manure from chickens fed 3‐nitro 4‐hydroxy phenyl arsonic acid as a feed additive is used as a soil amendment on Delawares sandy coastal plain soils.

The lead content of various plant species as affected by cycle‐lite™ humus 9

Abstract Four rates of Cycle‐Lite™ Humus ranging from zero to 50% of the soil volume were incorporated into a Lakeland loamy sand and a Matapeake silt loam. Selected test species were seeded immediately after incorporation of the humus and after a six month incubation. The Pb content of the top growth of plants grown in soil modified with this product was not elevated even though the humus contained 300 ppm of lead.

Nutrient concentration of corn as effected by poultry manure 1

Abstract The elemental composition of corn was evaluated during the 1973 growing season in an experiment with various rates of poultry manure. In general, the nutrient concentration of plant tissue reflected poultry manure applications with the exception of Mg which declined and Ca, Fe and Na which appeared to be largely unaffected. The elemental concentrations in the corn tissue were not in a toxic range however, the nutrient balance was changed by poultry manure application. Sampling of corn early in the growing season can be quite valuable with respect to predicting nutrient concentration of more mature corn for Mg, Mn, B and Zn, but it leaves much to be desired for the other elements tested.

Potassium release by some delaware soils 1

Abstract The A and B horizons of 29 Delaware soils were extensively cropped to sudan grass (Sorghum vulgare Pers. Piper) and corn (Zea mays L. Pioneer Brand Hybrid No. 3958) to evaluate the K release characteristics of these soils. Various chemical analyses were made on these soils. The double acid North Carolina extractant (NCE) was good at predicting K uptake during the early stages of the experiment and was most sensitive with A horizon soils. However, this extractant was not suitable for predicting K uptake in the latter part of the experiment when nonexchangeable K was more important. Boiling IN HNO3 was a good extractant in the latter part of the experiment when nonexchangeable K was being released and it also predicted K uptake from the B horizon well. Soils leached with 0.025M MgCl2 and incubated 25 days to determine K released were also highly correlated with plant uptake.

Potassium release characteristics and mineralogical characteristics of some delaware soils 1

Abstract Twenty‐eight agriculturally important Delaware soils were cropped intensively in a greenhouse experiment. There was no consistent positive correlation between K uptake and percent sand, silt, clay, clay minerals of the clay fraction, K‐feld‐spars of the sand fraction or K‐feldspar weathering of the soils from the A horizon. Only potassium feldspar from the sand fraction and K‐feldspar weathering correlated with K uptake in the soils of the B horizon. This correlation was only significant at the latter part of the experiment when nonexchangeable K was probably the source of plant available K.

Potassium fertilizer recommendations and changes in potassium soil test values as influenced by additions of potassium

Abstract The A and B horizons of 28 Delaware soils were incubated with 0, 200, 1000 and 2000 ug K/g of soil for one week, one, two and six months. Potassium soil test values were determined using the double acid extractant. The amount of K necessary to raise the soil test value one unit varied between five and 12 ug K/g of soil and was influenced by time of incubation, soil type, amount of K added and soil horizon. Correlation coefficients between the units of K necessary to raise the soil test values one unit and sand, silt and clay and cation exchange capacity are presented. Increasing soil test values to some predetermined point does not appear agronomically or economically sound for the Coastal plain soils of Delaware. Using this procedure to determine fertilizer K recommendations results in recommendations several fold higher than those recommendations which result from using field crop response to determine the amount of K fertilizer to be applied.

Photosynthetic capacity in potassium stressed soybean: Comparison of CO2 fixation and O2 evolution assays

Abstract Potassium deficiency in soybeans (Glycine max (L.) Merr.) may cause decreased photosynthetic capacity. Potassium‐stressed soybeans were compared by CO2 fixation and O2 evolution assays. Trifoliate leaves of potassium‐stressed soybean seedlings which did not show reduced chlorophyll content per unit fresh weight nor altered rates of light‐induced O2 evolution, fixed 38% less CO2 than did control leaves.