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Fluid Journal : Fall 2017
15 The Fluid Journal Fall 2017 The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Fall 2017 • Vol. 25, No. 4, Issue #98 Gudrun Mahrt Summary: Results of the 2016 fluidized calcium carbonate studies on spring wheat (club wheat) in Washington suggest that a limited but precise application of micronized calcium carbonate lime into the low pH soil strata can positively affect root development to overcome low soil pH stratification in no-till systems. In the North West of the United States, mainly Washington, Oregon, Idaho, Montana, but also the Canadian Provinces of Alberta and Saskatchewan (Figure 1), drought tolerant crops generate a substantial economic impact (Table 1). One major production area of that region is the dryland Palouse (WA, OR, ID) and is the focus of our current liming studies. Many of the soils here are young, developed from widespread loess deposits from windblown glacial dust some 10,000 years ago. The soil pH in the inland Northwest (Figure 2) has declined in direct proportion to the cumulative amount of applied fertilizer ammonium N. Nitrification of ammonium N from any source, commercial fertilizers, legumes, manure, gradually make soils more acid. Wheat can generally tolerate pH down to about 5.4, but legumes such as peas, lentils, or clover need a pH greater than 5.6 (Figure 3). Liming in this region still is not considered economical using conventional liming materials and application methods, but the subtle side effects of a lower pH, such as increased disease, soil aggregation and weed problems, may already cost more than is now realized. Native soil pH in much of the Inland Northwest, including the Palouse, is pH 7 (neutral). At such high pH aluminum is tightly bound to soil clay particles. However, at pH below 5.5 (more acidic), some Importance of Liming in Dry Land Palouse Cropping Systems ▼ DOWNLOAD Fluid lime (NuCal) shows benefits in Palouse studies. aluminum (and possibly manganese and iron) becomes plant available (exchangeable) and may be toxic to plant roots, reducing uptake of water and nutrients. This is a well studied effect. During the past many decades, farm management strategies of the inland Northwest included increased fertilizer use and new acid tolerant wheat varieties as a result of lower soil pH. While the use of lime to counteract acidity in high-input agriculture over the past 50 to 100 years has led to spectacular increase in yields (Rengel Handbook of Soil Acidity, 2003), dry-land farmers of the inland NW have never or very rarely considered the concept of liming fields. The Palouse cropping systems instead relied on wheat varieties and emerging breeding lines that are tolerant to aluminum toxicity (Kurt Schroeder, Mike Pumphrey 2013). This unfortunately is only a short term solution. Liming studies on aluminum tolerant varieties resulted in increased yields (up to 46 percent) compared to acid sensitive varieties. However, the high quantity of regularly available standard lime that was required in these initial pilot studies was deemed not economically feasible. The role of lime. There are several options to overcome soil acidity in the dry land regions. As an alternative to broadcast applications of large amounts of standard agricultural lime, pilot studies were initiated in 2011 examining in-furrow applications of prilled lime (CaCO3) with seed at planting at a rate of 150 lbs/A. An average gain of 3.3 bu/A was seen across all varieties (Wheat Life, January 2013). Lime applications, however, remain a rare event and growers are skeptical about effectiveness, experience application difficulties, incur problems in lime sourcing, and, of course, expect to see an additional work load, time, and equipment need, which all can lead to an unknown return on investment. Sound agronomy practices focus first on pH. The pH management is one of the most important factors for crop production. While it always seems to be overshadowed by the management of the macro-nutrients N, P, and K, the reality is that an improper pH has a major impact on soils and crops. Low pH is one of the more difficult soil conditions to fix within a short time frame. Growers are conditioned to fast results such as response to efficient N fertilizer application (Figure 4) Results from standard liming are unpredictable and low in performance. Micronized fluid and pelleted limes can work within a short time frame compared to standard lime sources. Agronomic practices (no-till, direct seed), topography of the region (steep slopes), and large quantities of standard lime required (adding cost of freight and material handling) limit growers’ acceptance of regular liming practices. The ideal solution for managing soil