Surface Broadcast and Incorporated Lime: Impact on Soil pH, Soil pH Distribution and Soybean Yield Response to Fertilizers
IPNI-1998-CAN-ON19
15 Mar 2001
Methodology
- The project will be initiated in fall 1997 on rented land at three sites to monitor the change in pH for two growing seasons. The sites selected will have pH values of 5.0 or less. Lime will be applied at one half the rate recommended to modify the top 15 cm of soil as determined by soil test. A one half rate of lime will be used as the material will be surface applied in no-till or mixed to approximately 7.5 cm into the soil instead of the traditional 15 cm. Sites of differing texture are to be located for comparison. Soybean planted in 75 cm row width will be used as the test crop in 1998 and corn at the same row spacing in 1999.
A split split plot experimental design will be used for statistical validity. The main split will consist of tillage (disc or no-till) with lime (ground or pelletized) as a split within tillage. No starter or NPK starter with or without a foliar manganese application will be randomized within the lime/no lime treatments. Each treatment will be replicated four times. Weed control will be provided by conventional pre-emergence herbicides (imazethapyr). Subplots will be 3 by 12 m with 6 m borders around the site. Manganese will be applied when deficiency symptoms are visible on soybean or in early July whichever is earliest.
Sufficient lime to achieve the desired pH will be broadcast applied in spring 1998 and tillage treatments, planting and other spring operations will be done according to conventional farming practices. Soybean in 1998 and corn in 1999 will be planted in conventional 75 cm wide rows to permit field operations. Rate of lime reaction with soil and depth of reaction (as measured by pH) will be followed from soil samples taken five times throughout the growing season. Samples will be collected prior to application of treatments for baseline measurements and site suitability. Other sampling date sin 1998 and 1999 will be at crop emergence, mid June, early July, Early August and immediately after harvest. Additional samples will be collected in the spring of 1999 and 2000 to determine changes over winter. Samples will be collected from the inter-row area and in the zone of tillage from planting operations. The zero lime and lime added plots will be sampled at each date.
Soil samples for pH determination will be collected from four depths at each sampling date. The 0-2.5 cm, 2.5-5 cm, 5-10 cm and 10-20 cm depths will be collected and analyzed separately to determine depth of reaction to lime. This will give an indication of pH change over time at the different sampling depths. To determine changes in nutrient availability from lime application, soil samples from the 0-15 cm depth will be sampled for pH, available P (Olson method), available K, Mg, Ca, Zn, Mn at three sampling dates. These depths were selected to coincide with traditional sampling depths for soil analysis for fertilizer recommendation so that the data will be directly transferable to producers. The dates will be pre-lime addition, pre-side dress and post-harvest to determine changes in available nutrients as a result of lime and starter fertilizer application.
Tissue samples in soybean will be collected at flowering in early August fro all plots and analyzed for N, P, K, Mg, Ca, Zn and Mn. The topmost fully expanded trifoliate leaf from the soybean plant will be analyzed.
Soybean and corn grain yields and grain moisture contents at harvest will be measured. Crop growth measurements will be taken throughout the growing season to determine the effects of lime treatment on the crop development.