Biosolids are stabilized solids from municipal wastewater treatment that meet federal standards for land application. Good estimates of biosolids N availability are needed to develop sustainable biosolids management programs. We conducted this study to (i) determine the availability and fate of biosolids N applied to a dryland soft-white winter wheat (Triticum aestivum L.)-fallow rotation, (ii) determine if N availability predictions for biosolids are applicable under dryland conditions, and (iii) make practical recommendations for biosolids management. We applied dewatered (21–30% solids) biosolids (4.3–5.5% total N; 257–853 lb N/acre) to on-farm test plots at three locations in the 9–12 in. rainfall zone of eastern Washington. Fertilized (anhydrous or aqua ammonia [AA]) and unfertilized treatments were established at each site for comparison. We measured yield and N uptake of grain and straw at harvest, and determined soil profile nitrate N (plus ammonium N, 0–12 in. depth only) before application, during fallow, and post-harvest. We determined apparent N recovery from the soil at the end of the fallow (ANRfallow). Nitrogen release from biosolids as measured by ANRfallow was dependable and consistent over the three sites, despite differences in environment among the sites. ANRfallow averaged 29%, similar to predicted values of 26–31%. The lowest biosolids rates (257–330 lb/acre) supplied more available N than AA. Yield, grain N, and flag leaf N all indicate that N was sufficient at the lowest biosolids rates used, and that higher levels of biosolids did not benefit the crop. Drawbacks to higher rates include risks of reduced crop yield (from moisture stress) and quality (from increased protein), and increased risk of nitrate movement below the root zone. Storage of nitrate in the soil profile does not appear to be a reliable strategy for supplying N for a second crop. Lower biosolids rates seem to reduce economic risks to the farmer and reduce leaching risk. Evaluation of low biosolids rates (100–300 lb total N/acre) and second crop response will be valuable in refining biosolids application recommendations. Research Question Biosolids are stabilized solids from municipal wastewater treatment that meet federal criteria for land application. Nitrogen is usually the key nutrient for determining biosolids application rates. Biosolids producers, farmers, and regulators need good estimates of biosolids N availability to develop sustainable biosolids management programs. Our objectives were to determine the availability and downward movement of biosolids N applied to soft-white winter wheat grown in a crop-fallow rotation, and make practical recommendations for biosolids N management. Literature Summary Standard EPA N availability estimates for biosolids are lower than estimates published in recent literature. Using the standard estimates to set biosolids application rates could lead to over-application of N, because they may underestimate N availability. Research in Montana and Colorado indicates that even when fertilizer inputs are low, some nitrate moves below the root zone in grainfallow cropping systems. Downward movement of nitrate is also possible in the Northwest, where precipitation falls mostly during the cooler months and soils are medium-textured. Excess applied N increases the potential for nitrate leaching. Also, excess soil N increases protein in wheat. High protein can be a problem in the Northwest, because most of the wheat grown is the soft-white type, which has highest quality at low protein levels. Study Description We established biosolids on-farm tests at three sites in the 9 to 12 in. rainfall zone of the Columbia Plateau of Washington, where wheat-fallow is the main cropping system. We used large (700-1000 ft long) plots to allow farmers to carry out normal field activities. We applied two to three rates (3–10 dry ton/acre; 257–853 lb total N/acre) of dewatered (21–30% solids) biosolids at the beginning of the fallow cycle, and compared biosolids treatments with aqua or anhydrous ammonia, and with unfertilized controls. Measurements included grain yield, grain protein, and grain N uptake, along with straw yield and N uptake, and flag leaf N concentration. We also measured plant-available N in the soil during the fallow, after harvest, and during the second fallow. Soils were sampled to a depth of 6 ft where possible to observe N levels throughout the soil profile. Applied Questions Were biosolids a reliable source of N? Yes. Nitrogen availability from biosolids was dependable and consistent over the three sites, despite differences in environment among the sites. We found that 29% of the biosolids N was in available form by the end of the summer fallow, compared with a predicted availability of 26 to 3l%, using EPA estimates. More N became available during the crop year. Is over-application of N a potential problem? Yes. The lowest rates of biosolids used in this study provided enough N for peak yields, with variable increases in protein and residual soil nitrate. Drawbacks to higher rates were reduced crop yield (from water stress) and quality (from increased protein), and increased risk of nitrate movement below the root zone. What is the agronomic application rate for biosolids N? Under the conditions of this study, agronomic rates appear to be lower than the lowest rates (257–330 lb/acre) we applied. Evaluation of lower biosolids rates (100–300 lb/acre total N) will be valuable in refining biosolids application recommendations for soft-white winter wheat grown in a dryland fallow rotation.