Agronomic Services

Crop Fertilization Based on North Carolina Soil Tests

Table 1.2  Manganese availability indices (Mn-AI) for manganese-sensitive crops*
Soil pH	Manganese Index from Soil Test Report
	5	10	15	20	25	30	35	40	45	50
5.4	22	25	28	31	34	37	40	43	46	49
5.5	21	24	27	30	33	36	39	42	45	48
5.6	19	22	25	28	31	34	37	40	43	46
5.7	18	21	24	27	30	33	36	39	42	45
5.8	16	19	22	25	28	31	34	37	40	43
5.9	15	18	21	24	27	30	33	36	39	42
6.0	13	16	19	22	25	28	31	34	37	40
6.1	12	15	18	21	24	27	30	33	36	39
6.2	10	13	16	19	22	25	28	31	34	37
6.3	8	11	14	17	20	23	26	29	32	35
6.4	7	10	13	16	19	22	25	28	31	34
6.5	5	8	11	14	17	20	23	26	29	32
6.6	4	7	10	13	16	19	22	25	28	31
6.7	2	5	8	11	14	17	20	23	26	29
6.8	1	4	7	10	13	16	18	22	25	28
6.9	0.68	2	5	8	11	14	17	20	23	26
7.0		0.8	4	7	10	13	16	19	22	25
* Mn-AI is calculated based on equation A  [101.2 + 0.6 Mn-I – 15.2 pH]  and rounded to the nearest whole number. The critical Mn-AI = 25. Manganese-sensitive crops include cotton, peanuts, small grains, soybeans, tobacco, melons, cucurbits, beans, onions, peas, peppers, radishes, rutabagas, strawberries, tomatoes, turnips and watermelons.
Hardy DH, Tucker MR, Stokes CE. 2008. Crop fertilization based on North Carolina soil tests. Raleigh (NC): North Carolina Department of Agriculture and Consumer Services, Agronomic Division. Circular No. 1.