Date of Award

8-2012

Level of Access

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Plant, Soil, and Environmental Sciences

Advisor

Marianne Sarrantonio

Second Committee Member

Greg Porter

Third Committee Member

Mark Hutton

Abstract

Broccoli yield and nutrient concentration were measured in plants grown in a field trial where soils were amended with different commercially available, bagged organic fertilizers in order to compare the effectiveness of these N sources. Yields were measured from plants grown in soils amended with blood meal, fish meal, pelletized dehydrated poultry manure, soybean meal, Chilean nitrate, or not amended with a source of N. Growth parameters of plants were measured throughout the growing season. NO3- and NH4+ concentrations were measured from soil samples obtained throughout the growing season to observe differences in N availability among treatments. Final yields were measured as total plant biomass (Mg ha-1), crown biomass (Mg ha-1), crown diameter (cm), hollow stem incidence and severity. Subsamples of broccoli crowns from each treatment plot were dried for measurement of crown nutrient concentrations.

Plants grown in soils amended with fish meal had a significantly larger (p<0.05) crown biomass than plants grown in soils amended with other N sources. In 2010, plants grown in soils amended with fish meal had significantly larger crown diameters than plants grown in soils amended with Chilean nitrate, blood meal or poultry manure and significantly larger (p<0.05) total plant biomass than plants grown in soils amended with poultry manure or soybean meal. More significant differences existed between treatments in 2011 than the previous year when N was a more limiting factor, likely due to a combination of poor soil quality, low N application rate and increased precipitation in early spring. In 2011, plants grown in soils amended with fish meal had significantly larger (p<0.05) crown diameter than plants grown in soils amended with blood meal or poultry manure and significantly larger (p<0.05) total plants yields than plants grown in soils amended with any other N source.

Very few significant differences (p<0.05) existed in crown micronutrient concentrations among treatment groups. Additional nutrient content of N sources did not have a significant effect on yield or crown nutrient concentration.

Few significant differences (p<0.05) in soil NO3- concentrations existed among N source treatments and the no-added N control treatment in 2010, indicating that preexisting N was sufficient. Soils amended with Chilean nitrate had an average NO3- concentration early in the growing season of 2010 that was nearly 3 fold the average concentration of other soils amended with other sources of N, but quickly declined. There was a much lower scale of NO3- availability in 2011, due to the aforementioned combination of factors, and few significant differences among treatments. Soils amended with fish meal tended to have higher concentrations of NO3- than soils amended with most other N sources throughout the growing season, but differences were not always significant (p<0.05).

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