Troy J. Dumler

Predicting Farm Tractor Values through Alternative Depreciation Methods

This study compares a variety of farm tractor depreciation methods to determine which most accurately estimates farm tractor values. These alternative depreciation methods consider different factors for estimating remaining value and vary in difficulty of use. Pairwise comparisons of mean absolute percentage error and forecast accuracy regression models were used to evaluate the accuracy of the depreciation methods, which depend on age, intensity of use, and manufacturer. Based on the results of this study, the Cross and Perry method was generally the most accurate. Copyright 2003, Oxford University Press.

Managing Diminished Irrigation Capacity with Preseason Irrigation and Plant Density for Corn Production

Many of the irrigation systems today in the U.S. Central Great Plains no longer have the capacity to match peak irrigation needs during the summer and must rely on soil water reserves to buffer the crop from water stress. Considerable research was conducted on preseason irrigation in the U.S. Great Plains region during the 1980s and 1990s. In general, the conclusions were that in-season irrigation was more beneficial than preseason irrigation and that preseason irrigation was often not warranted. The objective of this study was to determine whether preseason irrigation would be profitable with today’s lower-capacity groundwater wells at different levels of corn plant density. A field study was conducted at the Kansas State University Southwest Research-Extension Center near Tribune, Kansas, from 2006 to 2009. The study was a factorial design of preseason irrigation (0 and 75 mm), irrigation capacities (2.5, 3.8, and 5.0 mm d-1), and plant density (56,000, 68,000, and 80,000 plants ha-1). Preseason irrigation increased grain yields an average of 1.0 Mg ha-1. Grain yields were 28% greater when irrigation capacity was increased from 2.5 to 5.0 mm d-1. Crop water productivity was not significantly affected by irrigation capacity or preseason irrigation. Preseason irrigation was profitable at all irrigation capacities, although only slightly profitable at the highest irrigation capacity. Therefore, it may not be prudent to preseason irrigate with irrigation capacities of 5.0 mm d-1 or greater so that the water can be conserved for later use. At irrigation capacities of 2.5 and 3.8 mm d-1, a seeding rate of 68,000 seeds ha-1 was generally more profitable than lower or higher seeding rates. A higher seeding rate (80,000 seeds ha-1) increased profitability when irrigation capacity was increased to 5.0 mm d-1.

Volunteer corn in fallow

Introduction Volunteer corn is a common weed in the fallow phase of wheat-corn-fallow in western Kansas and the west central Great Plains. No-till increases precipitation storage, reduces soil erosion, and often increases crop yields when compared to conventional-till. As a result, many producers have adopted no-till cropping systems that use glyphosate extensively for weed control in fallow. Because most of the corn grown is herbicide-tolerant, volunteer corn in fallow may not be controlled with glyphosate. Failing to control weeds in fallow can reduce soil moisture storage and subsequent crop yield.

Optimal Corn Management with Diminished Well Capacities

Many of the irrigation systems today in the Central Great Plains no longer have the capacity to apply peak irrigation needs during the summer and must rely on soil water reserves to buffer the crop from water stress. Considerable research was conducted on preseason irrigation in the US Great Plains region during the 1980s and 1990s. In general, the conclusions were that in-season irrigation was more beneficial than preseason irrigation and that often preseason irrigation was not warranted. The objective of this study was to determine whether preseason irrigation would be profitable with today’s lower capacity wells. A field study was conducted at the KSU-SWREC near Tribune, KS, from 2006 to 2009. The study was a factorial design of preplant irrigation (0 and 75 mm), well capacities (2.5, 3.8, and 5 mm day-1 capacity), and plant population (55,000, 68,000, and 80,000 plants ha-1). Preseason irrigation increased grain yields an average of 1.0 Mg ha-1. Grain yields were 29% greater when well capacity was increased from 2.5 to 5.0 mm day-1. Water use efficiency was not significantly affected by well capacity or preseason irrigation. Preseason irrigation was profitable at all well capacities. At well capacities of 2.5 and 3.8 mm day-1, a seeding rate of 68,000 seeds ha-1 was generally more profitable than lower or higher seeding rates. A higher seeding rate (80,000 seeds ha-1) increased profitability when well capacity was increased to 5 mm day-1.

A comparison of forage yield and quality in a simulated graze-out for twelve varieties of hard red and white winter wheat

Six hard white winter wheat varieties (Burchett, Lakin, NuFrontier, NuHills, NuHorizon, and Trego) and six hard red winter wheat varieties (2137, Jagalene, Jagger, OK101, Stanton, and Thunderbolt) were planted in two southwestern Kansas counties, Clark and Stanton, to compare simulated graze-out forage yield and quality. Four replicated plots were planted in September 2003 for each variety at each location. Forage samples were collect from each plot during December 2003, March 2004, and April or May 2004. Dry matter content, dry matter yield, crude protein, acid detergent fiber (ADF), neutral detergent fiber (NDF), total digestible nutrients (TDN), net energy (NEm, NEg), relative feed value (RFV), and nitrate nitrogen were determined. Significant location-byvariety interactions were observed for most factors. Although significant differences in crude protein and energy were detected, it is unlikely that the performance of stock cattle would differ when grazing each of the varieties because the lowest crude protein concentration would support excellent gain, and because the differences in energy were relatively small.

Yield of irrigated cool-season grasses in southwestern Kansas

Nine varieties and a commercial mix of perennial cool-season grasses were planted in four replicated plots in two counties in southwestern Kansas to evaluate yield and adaptability when produced under irrigation. The varieties were smooth bromegrass, ‘Slate’ intermediate and ‘Hycrest’ crested wheatgrass, ‘Kentucky 31’ and ‘Max-Q tall fescue, ‘Profile’ orchardgrass, ‘Hykor’ festulolium, and ‘Dixon and ‘Lakota matua grass. The mix was Sharp Brothers’ ‘Pasture Mix #6’, a blend of smooth bromegrass, ‘Regar’ meadow bromegrass, Slate, Profile, and ‘Garrison’ creeping foxtail. Grasses were planted in September 2002. Forage samples were collected in the spring and fall of 2003 and 2004 to measure dry matter content and yield. Fall 2003 samples were not collected at Stevens County because calves grazed them. The greatest grazing preference was for orchardgrass. The least preferred was crested wheatgrass. Spring cuttings yielded less forage than expected in Ford County in 2004 and in Stevens in both years due to dry winters and higher than normal spring temperatures in 2004. Annual dry matter yields ranged from 10,565 to 13,694 lb per acre in Ford County during 2003, 5661 to 9032 lb per acre in Ford in 2004, and 6189 to 14,552 lb per acre in Stevens County in 2004. The consistently highest-producing grasses for both years were the fescues, intermediate wheatgrass, orchardgrass, and the pasture mix. The matuas had high yields in Ford County during 2003, but winter kill reduced the other spring yields. However, new grass plants from a high 2003 and 2004 seed production improved fall 2004 matua yields. The overall lowest-producing grass was crested wheatgrass.

Crop Water Allocation for Limited Ground Water

Irrigation scheduling decisions for irrigation managers with limited water resources are not made on a daily basis like those managers with fully irrigated systems. Irrigation managers with limited water supplies from restricted well capacities or water allocations need to anticipate crop selections, plan for crop rotations, and project water deliveries to each crop. A water allocation model, the Crop Water Allocator (CWA) has been built to evaluate growing season water allocations among 2 to 6 crops over 5 possible divisions of land area. Users input crop prices, production costs, irrigation costs, and maximum crop yields. The program iterates water allocation by 10% increments over all possible crop combinations and a chosen land division. Net economic return is calculated for each crop mix/ water allocation/ land division combination. Net returns are ranked and several of the highest are presented to the user for evaluation. The influence of one variable, such as commodity prices, crop yields, annual rainfall, irrigation system efficiency, and irrigation operating costs on net return can be evaluated through multiple executions of the model.

Effect of Irrigation Ending Date on Corn Yield and Irrigation Scheduling for Water Conservation

The results from a two-year field study indicate that the corn growers of western Kansas may not have to irrigate until black layer formation, as is the current practice. With the decline of Ogallala aquifer groundwater level and rising fuel cost any reduction of pumping makes economic sense. The first irrigation ending date was on August 10-15, corresponding to denting and starch layer formation of ¼ to ½ towards the germ layer resulted in yield that averaged 7 bushels per acre less than the second ending date on August 21-22, which corresponds to starch layer at ½ to ¾ towards the germ layer. However, continuing irrigation until September 1, corresponding to the start of black layer formation, improved yield by only 2 bushels per acre. A statistical analysis over the two years of data indicates that the first ending date is different from the last ending date, but the second ending date is not different from either first or last ending dates. Economic sensitivity tests show that irrigating until the formation of starch layer at ½ to ¾ towards germ layer is feasible with a corn price of

Transition to Dryland Agriculture

2 per bushel and

Using subsurface drip irrigation for alfalfa

6 per inch pumping costs. However, irrigating past this stage of grain development is not feasible even with