Location: Plant, Soil and Nutrition Research
Project Number: 8062-21000-044-002-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Aug 31, 2019
Objective:
The objective is to evaluate how a Great Plains cropping system impacts sustainable production of grain sorghum by measuring greenhouse gases/carbon sequestration and yield of sorghum grown in rotation with wheat at two western Kansas locations.
Approach:
Study sites will be located at the Northwest Research and Extension Center at Colby, KS and the Southwest Research Center at Tribune, KS.
a) Each study location will include 4 treatments with 4 replicates with one treatment being a control treatment.
b) The second treatment will receive N at a factor of 1.12 lb of N/bu based on the yield goal and adjusted for soil profile N as 32-0-0 solution applied with the planter as a surface stream at planting.
c) The third treatment will be the same as second treatment with the addition of a urease inhibitor.
d) The fourth treatment (K-State fertility recommendation) will receive N at a factor of 1.6 lb of N/bu based on the yield goal and adjusted for soil profile N as 32-0-0 solution applied with the planter as a surface stream at planting.
These plots will be established in a field under standard rotation of grain sorghum fallow wheat fallow such that the grain sorghum will be planted into wheat stubble from the 2018 wheat harvest.
N2O emission will be measured by a vented chamber technique. Chambers will be installed directly after fertilization and emissions will be measure every two days for 1 week followed by weekly measurements during the growing season and every two weeks during the winter fallow period and weekly during the summer fallow period.
Emissions measurements are achieved by placing the chamber lid on the chamber and immediately collecting the time zero headspace sample. Three additional headspace samples are collected on 15 min increments. These samples are stored at stable temperature and analyzed using a gas chromatograph. The resulting headspace concentrations are regressed against time and the resulting slope is used to calculate the N2O flux during that measurement event. Linear extrapolation is used to estimate flux between sampling points and then season emissions are estimated.
The difference between N2O emitted from the control and fertilized treatment will be used to estimate the N2O emission factor per unit of N applied.
Grain yield will also be measured to understand its response to added fertilizer N and the corresponding N emissions.
