Illinois
Fertilizer Conference Proceedings
January 25-27, 1993
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Kenlyn N. Clark, Ted R. Peck, and John E. Sawyer1
The increasing use of no-till practices by producers to control erosion and meet government program mandates has raised questions about the best management practices for limestone application in no-till fields. This study was initiated to compare crop response, soil profile pH and chemical characteristics of surface-applied limestone and plow-layer distributed limestone in a no-till system. The effects of limestone material, application rate, surface application versus plow-layer distributed limestone, and corrected pH on crop grain yield, grain moisture, plant nutrient concentration, and the soil profile chemical characterization are being investigated at the Brownstown Agronomy Research Center, on a Cisne silt loam soil (Fine, Montmorillonitic, mesic Mollic Albaqualf).
Traditional moldboard cultivation allows easy incorporation of liming materials into the plowlayer when needed to correct low soil pH. The growing producer trend toward reduced till, and especially no-till, tillage systems, however, raises questions about the most effective placement of limestone under such tillage practices. Other researchers have found increases in profile stratification of nutrients and soil pH as the amount of tillage decreases or is eliminated, especially as the frequency of moldboard plowing decreases (Hoeft and Randall, 1985; Buchholz et al., 1986; Sawyer and Carter, 1989). The increased stratification or reduced distribution of nutrients and pH has not always translated into reduced grain yield, but these studies were usually confounded because the tillage comparisons were made when the tillage system itself had caused the stratification. If production levels vary with different tillage systems, it is very difficult to determine variations due to tillage and those caused by depth stratification of nutrients or soil pH.
Research has been conducted to determine the effect of surface limestone application on crop production and soil pH distribution in continuous no-till corn Z ma L.) (Triplett et al., 1972; Moschler et al., 1973; Blevins et al., 1978; Sutton and Trierweiler, 1990). These studies, however, did not compare no-till systems where the limestone was distributed through the plow layer versus applied to the soil surface. Also, these studies were conducted using only surface application of N. Reed and Eckert (1989) found zones of low pH at the point of repeated injection of anhydrous ammonia in a no-till continuous corn system (pH below 5.0 after eight years and injection was at the same point each year). Corn yield was not affected but elevated concentrations of Mn were found in ear leaves at silking. This research points out the possible deleterious effect of low pH below the soil surface if only surface applications of limestone are made in a no-till system.
Producers need information on the impact of surface applications of lime on the level of production in no-till systems before they adopt this management practice. Will plant roots adequately explore and obtain nutrients from the soil throughout the profile if only the surface few inches are maintained at the proper pH level and not throughout the plow layer?
In a review of limestone use and soil pH, McLean and Brown (1984) and Barber (1984) do not thoroughly address this question. Most comments stated that either limestone should be added to the plow layer before initiation of reduced tillage or surface applications of lime should be made to correct acidity from surface applications of N fertilizers. Blevins et al. (1978) stated that if the soil pH is at a critical low level, then it may be advisable to incorporate limestone before initiation of a no-till system. However, they did not study that situation in their research. As producers decide to utilize no-till in their production programs, the question of limestone distribution must be addressed to ensure that high levels of production can be maintained.
The general goal of this project is to determine the effects of soil profile
pH stratification on crop production and soil chemical characteristics within
a no-till system. Specific objectives are to (1) compare profile soil pH and
other soil chemical characteristics between surface limestone application and
plow layer distributed limestone (past limestone application) in a no-till continuous
corn rotation, (2) determine plant nutrient concentration and yield with surfaceapplied
limestone and plow-layer distributed limestone in a no-till system.
This study utilizes an existing liming materials experiment at the Brownstown Agronomy Research Center, located in south central Illinois. The soil type is a Cisne silt loam (Fine, Montmormillonitic, mesic Mollic Albaqualf). Past treatments included a control or no lime application, pelletized lime application at 500 and 1000 lb. CCE/acre, powdered lime at 3.25 and 4.75 tons CCE/acre, and ag-ground limestone at 6.5 and 9.5 tons CCE/acre. These treatments were replicated three times in a randomized complete block design and were applied on Aug. 20, 1985. Past tillage has been a minimum till and chisel plow. Soil pH levels (0-6 inch depth) at the initiation of the study were 4.4 to 4.5 for the control, and 6.1 to 7.1 for the high rates of powdered and ag-ground limestone.
In the fall of 1989, the plot area was fertilized with 63 1b.P205/acre and 1201b. K20/acre and then chisel plowed. In the spring of 1990, 721b. P205/acre and 2301b. K20/acre were applied and then the entire area was moldboard plowed (depth of 6 in.). Soybeans were grown in 1990.
Soil samples, 0-6 inch composite and by 2-inch increments to a depth of 12 inches, were collected Oct. 31, 1990 from all plots before limestone application. Limestone treatments were applied Nov. l, 1990 to the soil surface of the three original low limestone rate treatments.
Corn was planted in the spring of 1991. Soil samples were collected April 24 and October 15: both 0-6 inch composite and by 2-inch increments to a depth of 12 inches. The yearly 1.1 ton CCE/acre surface lime application was done after sampling was complete.
The continuous corn rotation was maintained in 1992. Soil samples were taken on April 28 and October 19. The yearly 1.1 ton CCE/acre surface lime application was made after sampling was completed.
Newly applied limestone treatments were 3.25 ton CCE/acre rate of powdered lime (99.4 percent through a 60 mesh sieve). 6.5 ton CCE/acre rate of ag-ground limestone (93.4 percent through an 8 mesh, 50.0 percent through a 30 mesh, and 33.3 percent through a 60 mesh sieve) and an annual application of 1.1 ton CCE/acre powdered lime (99.4 percent through a 60 mesh sieve) applied for three years. All treatments will remain in the same location each year. Plot size is 15 by 60 feet. The experimental design is a randomized complete block with three replications.
The intent is to measure grain yield, grain moisture content at harvest, and
nutrient concentration of leaf, whole plant, and grain samples. Soil profile
chemical characterization over time will be measured for pH, Ca, Mg, and micronutrients.
The current proposed duration of this project is for three years. Continuation
of the project beyond that time may be necessary to measure longterm effects
of limestone application.
Corn yields for the 1991 and 1992 crop years are reported in table 1. Generally good crop yields were obtained but treatment replication was poor, probably contributing to the non-significance of any treatment.
Irrigation was delayed in 1992, and this may have affected the crop stand. Spotty reduced growth of plants was associated with delayed tassel emergence, as shown in table 2.
Chemical analysis of the soil samples from the spring of 1991 shows stratification
of pH and nutrients in the plow layer (Table 3). No
correlation between stratification and crop growth has been noted to date.
Table 2: Plant height and percent tasseling on July 7, 1992
Table 3: pH values of soil samples
1Graduate Research Assistant and Professor, Dept. of Agronomy, Univ of IL, and Manager Agronomy Services, GROWMARK, Inc., respectively.
Sawyer, J.E., and T.R. Peck. 1991 Comparison of Plow-Layer Distributed and SurfaceApplied Limestone for No-Till Crop Production, page 95-100. In 1991 Illinois Fertilizer Conference Proceedings, Edited by R.G. Hoeft, Springfield, IL., Jan. 28-30, 1991.
