Covariance Structures in Conventional and Organic Cropping Systems

Table 6

Conventional (CNV) and organic (ORG) cropping systems pairwise dissimilarity (covariance) matrix correlation statistics based on whole systems, crop rotations, tillage-fertility treatments within 2-year and 4-year crop rotations, and phases within 2-year and 4-year crop rotations. Covariance matrices were derived from cumulative yield, temporal yield variance, and coefficient of variation of two rotation cycles in a long-term field experiment.

Factor	Comparison	MSS		𝑟-value	𝑡-value	P (random 𝑧≥observed  𝑧)	P (random 𝑧≥observed  𝑧)
		CNV	ORG				10^3 permutations
Systems		3090	6070	0.43	1.60	0.06	0.035
Rotations	2-year	16196	6423	0.19	0.71	0.24	0.207
	4-year	935	6830	0.53	1.97	0.03	0.028
Tillage-fertility
2-year rotation	CTNF	32275	5192	0.68	2.67	0.01	0.003
	CTYF	42788	4659	0.79	2.93	0.01	0.013
	STNF	3673	32110	−0.04	−0.13	0.56	0.768
	STYF	12443	5964	0.93	3.27	0.01	0.006
4-year rotation	CTNF	937	816	0.65	2.42	0.01	0.002
	CTYF	2031	2824	0.52	2.16	0.02	0.002
	STNF	1859	11938	0.04	0.16	0.44	0.367
	STYF	411	9257	0.51	0.93	0.03	0.046
Phase (rotation)
2-year rotation	CSCS	784	8847	0.27	0.85	0.16	0.153
	SCSC	950	3265	0.71	2.64	0.01	0.001
4-year rotation	ACSW	3025	8415	0.08	0.32	0.38	0.345
	CSWA	2040	5293	0.96	3.47	0.01	0.001
	SWAC	704	3003	0.33	1.18	0.12	0.087
	WACS	501	6623	−0.31	−1.17	0.88	0.825