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The presence of biologically active substances (BAS) in biosolids may enhance plant stress tolerance and growth, but the underlying mechanisms are not well understood. This greenhouse study investigated the effects of untreated biosolids, containing 2.1 μg indole‐3‐acetic acid (IAA) g−1, and tryptophan‐treated biosolids, containing 15.4 μg IAA g−1, on tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] drought resistance. Treatments included a fertilizer control, indole‐3‐butyric acid (IBA) at 2 μM (hormone control), treated biosolids (2.95 g kg−1 soil), and untreated biosolids (2.97 g kg−1 soil). Nitrogen availability was equalized among treatments, and tall fescue physiological responses were measured under well‐watered or moisture stress conditions. Treated biosolids improved turfgrass quality and root mass under both soil moisture regimes and delayed leaf wilting under moisture stress. At the end of the second drought cycle (2 February), treated biosolids improved quality and photochemical efficiency by 18 and 26% relative to the control. Treated biosolids increased leaf IAA by 122 and 52%, respectively, and trans‐zeatin riboside by 100 and 189%, respectively, during each of two maximum drought periods. Leaf tissue increases of IAA and cytokinin were associated with greater content of these hormones in the soil. The data suggest that biosolids application may alter growth hormone (IAA and cytokinin) content and improve plant drought resistance.

Application of broiler (Gallus gallus domesticus) litter to grasslands can increase ammonium (NH4-N) and dissolved reactive phosphorus (DRP) concentrations in surface runoff, but it is not known for how long after a broiler litter application that these concentrations remain elevated. This long-term study was conducted to measure NH4-N and DRP in surface runoff from grasslands fertilized with broiler litter. Six 0.75-ha, fescue (Festuca arundinacea Schreb.-)bermudagrass [Cynodon dactylon (L.) Pers.] paddocks received broiler litter applications in the spring and fall of 1995-1996 and only inorganic fertilizer N in the spring of 1997-1998. Surface runoff from each paddock was measured and analyzed for NH4-N and DRP. Broiler litter increased flow-weighted NH4-N and DRP concentrations from background values of 0.5 and 0.4 mg L(-1), respectively, to values > 18 mg L(-1) in a runoff event that took place immediately after the third application. Ammonium concentrations decreased rapidly after an application and were not strongly related to time after application or runoff volume. In contrast, DRP concentrations tended to decrease more slowly, reaching values near 1 mg L(-1) by 19 mo after the last application. Dissolved reactive P concentrations decreased linearly with the natural logarithm of days after application (p<0.03), and increased linearly with the natural logarithm of runoff volume (p<0.0001).

Cover crops are integral parts of whole farm systems that include corn (Zea mays L.), but there is a lack of synchrony between cover crop N release and corn N uptake. This synchrony may be enhanced by varying the cover crop spring desiccation time and subsequent residue management. A field study was established to determine (i) the effect of rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), and rye + hairy vetch spring desiccation timing on cover crop biomass, N content, and C:N ratio and (ii) the effect of the cover crop species, spring desiccation timing, and residue management on soil moisture content, soil mineral N concentration, corn tissue N concentration, and corn grain yield. Chemical desiccation times were either the boot stage of rye (approximately 3 wk prior to corn planting) or the early flowering stage of hairy vetch (several days prior to corn planting) for all three cover crop treatments. Three cover crop residue management treatments were implemented several days after each chemical desiccation: no further treatment (control), cover crop residue mowed (mow), or cover crop residue mowed and disked (mow + disk). All cover crops increased in biomass accumulation, but only hairy vetch increased in N content between desiccation times. Cover crop N availability was more important for corn yield potential than cover crop soil moisture conservation. Corn yields were higher following hairy vetch than following rye and rye + hairy vetch, due to greater N availability from hairy vetch residue. Corn N concentrations and yields were not influenced by desiccation time following hairy vetch, indicating that hairy vetch should be allowed to grow until immediately prior to corn planting, to permit maximum N accumulation. However, corn N concentrations and yields were higher with early desiccation than late desiccation following rye and rye + hairy vetch, indicating that cover crops including rye should be desiccated several weeks before corn planting. Mowing may be an alternative cover crop management technique that enhances the synchrony of cover crop N release with corn N need and uptake while maintaining a moisture conserving mulch.