Document Type

Thesis - University Access Only

Award Date

2011

Degree Name

Master of Science (MS)

Department / School

Plant Science

Abstract

Manure can be an important source of plant nutrients for crop production and may improve soil quality. Management practices such as methods of applying manure, timing of manure application, tillage, cover crop use and their interactions with landform and climate play an important role in nutrient losses from agricultural fields. Our research objectives were 1) to determine the influence of tillage and manure application timing on nutrient loss in snowmelt run-off and 2) to determine the effect of cover crop on nutrient loss in simulated rainfall runoff with manure use. Two separate field studies were conducted to meet these objectives. For objective one a study was designed to compare three dates of beef feedlot manure application at 40 tons/hectare on untilled and tilled soybean stubble. Eight 4 m2 steel frames were installed in the fall on each tillage area to define individual plots. Treatments were randomly assigned so that each area had two control plots, two that received manure during November, two in January, and two in March. Snow melt runoff volume (RO) was recorded during March and sub-samples analyzed for ammonia (AM), nitrate nitrogen (NT), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), total phosphorus (TP) and total dissolved phosphorus (DP) from the run-off of each plot. Soil probes were installed at 15 cm (6in) and 50 cm (20 in) below the soil surface to monitor soil moisture and temperatures for each plot. Snow accumulation before and after manure application was measured. Mean comparisons of tillage and manure timing were determined with SAS PROC GLM. Snow melt runoff concentrations and loads of AM, TP and DP trended higher in runoff from manure application treatments compared to the control. The concentration and load ( calculated as runoff volume/area x concentration) of AM was significantly (LSD 0_1) higher with tilled compared to untilled plots. The November application significantly increased RO amount, AM concentrations and AM, NT and DP load in the snowmelt runoff compared to winter applications. For objective two, a field study was designed to compare cover crop (rye) used after com with and without (liquid swine) manure at ~59,325 L ha-1. Steel frames (from objective one) were used to define sixteen 4 m2 plot areas. Treatments were randomly assigned so that each replication had one manure treatment under cover crop, one non-manure under cover crop, one manure treatment without cover crop and one non-manure treatment without cover crop. Two rain simulations (the first defined as "dry" and the second ''wet") were conducted during May 2010 and analyzed for the same parameters as in objective one except AM was not determined. Significant treatment effects and mean comparison were done with LSD (0.I0)· Runoff under manure treatments had significantly (LSD o. 1) higher concentrations of NT, TSS, TP and DP in both runoff runs. The dry run loads of NT, TSS and DP were significantly higher in the manured treatments while NT was found significantly greater in the wet run. With both dry and wet runs the concentration and load of NT was significantly lower in runoff water with the cover crop compared to no cover crop treatment. In addition TKN concentration under the wet run was lower with the cover crop treatment.

Library of Congress Subject Headings

Farm manure--Management

Plant nutrients

Crops-Nutrition

Runoff

Format

application/pdf

Number of Pages

79

Publisher

South Dakota State University

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