Year: 2016
Type: dissertation
Abstract: Cover crops have numerous benefits and while cover crops have been used for centuries, currently there are few producers in Kansas growing them and so there is a need for additional research on how cover crops affect soil properties, and on the potential for utilizing cover crops as forage.Two studies are presented in this thesis.The first study evaluated the use of cover crops in a vegetable production system as compared to a fully tilled control.This study evaluated soil physical properties in the form of wet aggregate stability and infiltration, and microbial properties by soil microbial biomass carbon (MBC).Over the three year study, the most pronounced differences observed were in the wet aggregate stability between the cover crop and control treatments where the cover crop treatments had better soil aggregation compared to the control.At the conclusion of the study, there was not a difference between fall and spring planted cover crop treatments.The second study evaluates species composition and forage quality of various combinations of multi-species cover crop mixtures.This study evaluated sixteen treatments, each consisting of a three-way mixture of a brassica (turnip or radish), grass (rye, wheat, barley, oat), and a legume (berseem clover or Austrian winter pea).Species composition analysis found that the brassica species dominated the mixtures (60-80% by mass on a dry weight basis) in 2014 while the grass species were dominant (62 -67%) in 2015.Overall all treatments produced prime quality forage (as compared to hay values), however some treatments cost significantly more to plant than others.Therefore an economic analysis compared the treatments and found that the treatments containing turnips and oats generally provided the best return on investment given that both of these species were among the cheapest to plant and produced moderate to high biomass compared to the other treatments.The results of these projects point to the potential benefits that cover crops can have for producers interested in improving soil or utilizing cover crops for forage.v Chapter 1 -Cover Crop Effects on Soil Properties in a Three-Year No-Till Pumpkin Experiment Abstract Vegetable crop production typically involves smaller acreages than agronomic production but relies heavily on intensive cultivation of soil to manage weeds and prepare the seedbed for planting.Over time, extensive tillage can have negative effects on soil structure and microbial properties, because soil is more prone to erosion when aggregation is reduced, and nutrients cycle most efficiently with a healthy microbial community.Conservation agriculture refers to production practices which lend themselves to sustainability.This three-year study evaluates the use of cover crops and the practice of no-till in pumpkin production.For this study, no-till is defined as the pumpkin cash crop no-till planted into a terminated cover crop residue mat.Treatments were a control (no-cover crop, and tilled ≥ twice annually); the other seven treatments were either a fall-planted cereal rye or rye mixed with other species, or springplanted oats or oat/pea mix.Soil wet aggregate stability was determined by wet sieving.Microbial biomass carbon and dissolved organic carbon were determined using the 0.5 M K2SO4 extraction method.The main soil physical property that was affected by cover crops in this study was an improvement in soil aggregation, while lesser effects were observed for water infiltration and bulk density.Soil aggregation improved over the duration of this study at both sites.While these changes did not occur immediately, soil aggregation showed differences between cover crop treatments (tilled once/year) compared with the control (tilled ≥twice/year).The cover crop treatments were first planted in fall 2012 but the differences between the control and the cover cropped treatments were not statistically significant until fall 2014 for Olathe and spring 2014 for Wichita.These differences continued to become more pronounced at both sites throughout the remainder of the study.This study illustrates the potential for conservation agriculture practices as having a positive effect on soil health, and for some parameters, this change can happen in as little as 1.5 to 2 years.
Author: C. Davis
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDGs: Zero hunger, Life on land
Open Access status: green
OpenAlex ID: W2596989141