The importance of accounting method and sampling depth to estimate changes in soil carbon stocks

Table 1 Century treatment descriptions^a

Century maize treatments^b
CMT	Conventional maize–tomato with synthetic fertilizer, pesticides, and winter fallow
CMT + WCC	A hybrid system with synthetic fertilizer, pesticide, and a winter cover crop (WCC)
OMT	Certified organic maize–tomato with composted poultry manure and WCC
Century wheat treatments^c
RW	Rainfed wheat–fallow control with no additional inputs
RW + N	Rainfed wheat–fallow and N fertilizer
RW + WCC	Rainfed wheat–fallow with WCC planted after wheat harvest and terminated before summer fallow
IW	Irrigated wheat–fallow with winter supplemental irrigation and no fertilizer inputs
IW + N	Irrigated wheat–fallow with supplemental irrigation and N fertilizer

^aAcross all Century treatments, disking operations were restricted to 15–20 cm depths, and tillage was conducted to a maximum depth of 25 cm. Soil sampling across all treatments occurred in fall prior to any tillage event
^bPost-harvest residues for both the maize and tomato rotations were disked into the soil. Tomato seedlings were started in greenhouses and transferred to beds prepared by listing and rolling. WCC were terminated by mowing and incorporated with 2–3 disking operations
^cPost-harvest wheat residues across all wheat treatments were incorporated by two shallow disking operations in summer. For treatments with fallow, four disking operations occurred after wheat harvest to manage weeds. WCC were terminated with 2–3 disking operations

ISSN: 1750-0680