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Meta‐Analyses of Biosolids Effect in Dryland Wheat Agroecosystems
Author(s) -
Barbarick Kenneth,
Ippolito James,
McDaniel Jacob
Publication year - 2017
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2016.12.0470
Subject(s) - biosolids , agronomy , fertilizer , agroecosystem , environmental science , nutrient , sewage sludge , crop rotation , chemistry , crop , zoology , sewage , agriculture , environmental engineering , biology , ecology , organic chemistry
Land application to cropping systems is USEPA's preferred method of recycling biosolids. Determination of biosolids effect size through meta‐analyses from two decades of field‐location research at three sites should answer the question: Does 20 yr of biosolids application affect dryland wheat ( Triticum aestivum L.) grain production, grain nutrient concentrations, and soil elemental extractability compared with equivalent rates of commercial N fertilizer? At two sites, biennial biosolids application rates to a wheat–fallow (WF) rotation were up to 11.2 dry Mg ha −1 and up to 112 kg commercial N fertilizer ha −1 , whereas rates at the third location varied to match soil‐test information. Crop rotations included WF and wheat–corn ( Zea mays L.)–fallow. We completed meta‐analyses of biosolids effects compared with N fertilizer on wheat yield, grain protein, grain total, and soil ammonium bicarbonate‐diethylenetriaminepentaacetic acid (ABDTPA)‐extractable P, Zn, Cu, Fe, and Ni concentrations at the aforementioned sites from 1993 through 2013. Results showed that biosolids produced greater grain P and Zn at one site. Biosolids rates at two sites resulted in greater grain Zn and ABDTPA P, Zn, Cu, and Fe. Meta‐analyses tests for heterogeneity indicated that the variance for all sites and rates could be explained as consistent across treatments, whereas the test for the 20 yr showed that heterogeneity was large and other factors affected the variance (e.g., climatic variability between years). Meta‐analysis showed the practical effect of biosolids over a 20‐yr study and demonstrated that the primary biosolids effect was an improvement in Zn availability to wheat. Core Ideas Meta‐analyses provided effect size for wheat yield and grain and ABDTPA concentrations. Grain and ABDTPA levels were increased by biosolids application compared to N rates. Inconsistent results over years were probably due to climatic vagaries.