Ag and Pelletized Lime

Soil pH is the cornerstone of a good crop production fertility program. Soil pH indicates acidity and alkalinity. Most crops grow best in soil with pH from 6.0 to 7.0. Soil test results showed that 26% of the samples sent to the University of Missouri Soil Test Laboratories in 1997 had soil pH values less than 5.4 and needed lime to correct the acidity. Applying lime is an expensive input for cotton producers. In Missouri, farmers can choose from agricultural lime produced at several quarries which mine limestone with different Mg contents.

A cotton field study was conducted at Portageville, Mo to compare dolomitic lime from Peidmont, Mo quarry (red) and calcitic lime from Jonesboro, IL quarry (white) for correcting soil pH in an acid cotton field . The initial soil pH (salt) in the field was 5.1. Lime rates in treatments with red and white lime were adjusted to make them equivalent based on calcium carbonate equivalents and fineness of the lime material. Although white lime caused a more rapid pH increase than red lime in 2000, neither lime treatments resulted in statistically higher yields than the untreated check. Three-year average lint increase from lime compared to the check was 85 lb lint per acre for white lime and 101 lb lint per acre for red lime. Using 52 cent a pound cotton, the gross return from applying lime averaged $44 to $53 per year. A 12-week laboratory incubation experiment was also conducted comparing pH change in an acid soil treated with lime from four lime quarries (Tipton, Auvasse, Peidmont, and Jonesboro). Soil pH tests showed that after 4 weeks, pH in soil treated with dolomitic lime from Peidmont was significantly lower than pH in soil treatment from the other three quarries. However, at 12 weeks, all the incubated soil samples treated with different lime material were above pH 6.0 and were significantly higher pH than the untreated check. The soil treated with Jonesboro lime had the highest pH among the treatments.

A second experiment was conducted to determine whether long-term use of dolomite lime, which reduces exchangeable soilCa:Mg ratios, would decrease plant K+ uptake and cotton yield. To produce a range of Ca:Mg ratios in a soil with near neutral pHsalt (6.2), selected rates of gypsum (CaSO4) and Epsom salt (MgSO4) were applied and incorporated in plots. Soil Ca:Mg ratios ranged from 2.5:1 to 7.6:1 (% base saturation). Whole plant tissue K, fiber quality, and lint yield were not significantly affected by exchangeable Ca:Mg ratios. This study showed that cotton farmers with well-drained Delta soils should not be concerned about potential negative effects of Mg in dolomite lime material. MORE DETAILS.

In recent years, agricultural fertilizer dealers have reported 2 to 3 fold increases in sales of pelletized lime. Pelletized lime is finely ground limestone, which is made into small pellets for broadcasting with conventional fertilizer equipment. Because pelletized lime is relatively expensive per ton, it is applied at lower rates (<300 lbs/acre) as compared to recommended rates of agricultural lime. A “1:10 ratio” rule of thumb has been promoted for comparing the short-term neutralizing effectiveness of pelletized lime to agricultural lime. (Example: if a soil test recommends the ENM equivalent of 2000 lbs of agricultural lime per acre apply 200 lbs of pelletized lime/acre). Most farmers realize that pelletized lime is not a long-term “fix”, but expect it to reduce soil acidity to tolerable levels for one year. Typically, farmers apply this material on fields that a landlord is unwilling to share part of the cost of applying agricultural lime or will not provide a lease agreement for more than one year.

A study was initiated to evaluate the general philosophy of using finely ground lime to provide a short-term, “quick fix” of soil acidity and compare corn and cotton yield response of pelletized lime to agricultural lime. Soil samples collected in early May of 2005 showed 1209 ENM/acre was needed. Ag lime (514 ENM/ton) and pelletized lime (720 ENM/ton) were applied to 10’ X 40’ plots with four replications. Lime materials were incorporated with tillage before soybean planting. Each lime was evaluated at ¼ recommended ENM, ½ recommended ENM, ¾ recommended ENM, and 100% of the recommended ENM per acre. Pelletized lime treatments were included with low rates dribbled over the seed furrow behind the planter press wheel and applied directly in the seed furrow with soybean seeds.

Soybean harvested in October showed that both lime sources increased soybean yields compared to checks when at least 50% of recommended lime was applied but the very low rates often used with pelletized lime was not effective

A second test site was located in 2006 with a soil pH of 4.9. Soil tests showed that approximately 2 tons of ag lime was needed to correct soil pH. Four rates of ag lime and four rates of pelletized lime were applied broadcast. Each pelletized lime rate was 1/10 of a corresponding agricultural lime treatment. Corn with agricultural lime increased in yield 20 to 45 bushels per acre. Yields from pelletized lime were averaged less than 5 bushels greater than untreated checks.

Lime	MU Rec % applied	Material per acre	Soybean bu/acre
	MU Rec % applied	Material per acre	Soybean bu/acre
Check	0	0	27
Ag lime	6	0.1 ton	30
	12	0.3 ton	34
	25	0.6 ton	30
	50	1.2 ton	41
	75	1.7 ton	39
	100	2.3 ton	44
Pell lime	6	0.1 ton	30
	12	0.2 ton	35
	25	0.4 ton	26
	50	0.8 ton	31
	75	1.3 ton	28
	100	1.7 ton	39

Lime	Material	Corn
	per acre	bu/acre
Check	0	98
Ag lime	0.5 ton	126
	1.0 ton	123
	1.5 ton	145
	2.0 ton	121
Pell lime	100 lb	100
	200 lb	96
	300 lb	98
	400 lb	103