A primary objective in Agronomy is to increase crop yields through improved varieties/hybrids and production practices. Crop variety/hybrid performance tests of irrigated corn, irrigated wheat, dryland wheat, irrigated grain sorghum, dryland grain sorghum, and irrigated soybeans were conducted at the Southwest Research Extension center in Garden City, Kansas annually over the last 50 years. For each crop, the varieties/hybrids yields were averaged for each year from 1956 through 2006. These trial averages were regressed against year to measure the level of crop yield improvement throughout the last 50 year period. The greatest crop improvement has clearly occurred in irrigated corn. During this time period irrigated corn yields increased 138 kg/ha/year (P≤0.0001). Corn yields increased primarily through improved corn hybrids. Corn yields were also increased through improved fertility management, weed control practices, insect resistance, and increased plant populations. Irrigated and dryland wheat yields increased 19 kg/ha/year (P≤0.07) from varieties with reduced lodging, earlier maturity, increased disease resistance, and improved yield potential. Wheat yields were highly variable throughout the 50 year time period due to environmental conditions. Hot temperatures during grain fill, spring time freezes, rust, and hail reduce and cause significant year to year yield variation. In addition, seasonal precipitation variation contributes to yield variability observed in dryland wheat varieties. These environmental challenges likely mask some of the yield improvements made in wheat varieties. Irrigated grain sorghum has consistently yielded an average of 6,300 to 8,800 kg/ha, and dryland grain sorghum yield increased 42 kg/ha/year (P≤0.001). Sorghum yields were improved through varieties with reduced lodging and improved yield potential, and better production practices. Irrigated soybeans have increased 15 kg/ha/year (P≤0.06) from varieties with higher yield potential and greater tolerance to iron chlorosis. Variety/hybrid performance tests have and will continue to assist producers make decisions of what varieties or hybrids to plant.