Biosolids Application for Barley Production

Abstract

Biosolids with different loading rates were applied to soil planted with rainfedbarley to study the effects of applying biosolids on soil and on barley’s straws andgrains yield. Randomized Complete Block experimental design was employed with 5treatments. This included a control and four replicates to test the null hypothesis whichstates that there is no significant difference between treatment means on crop and soilparameters vs. the research hypothesis which states applying biosolids to land plantedwith rain-fed barley affects both soil and crop parameters. Biosolids loading rates were0 as a control, 2, 4, 6, and 8 metric tons/ha. Soil at the testing site had a high clay content in the sub-soil and relatively lower claycontent on the surface, probably due to wind erosion. The soil was slightly calcareouswith lime content increasing with depth and with a slight alkalinity. Organic matter andphosphorus contents of soil were low with colors that varied from reddish brown to yellowishbrown. At harvesting time, there was no significant differences in grain yields at different biosolidsloading rates with a p-value of 0.52. Average grain yields of 2.86, 3.37, 3.4, 3.57,and 3.20 tons/ha were measured at biosolids loading rates of 0, 2, 4, 6, and 8 tons/ha,respectively. Average grain yield of 3.00 for a recommended inorganic fertilizer rate of diammoniumphosphate and Urea traditionally applied at rates of 90 kg/ha and 20 kg/ha,respectively, showed a yield higher than the 0 biosolids loading rate. However, it waslower than all other biosolids loading rates. It was determined that applying biosolids to soils planted with rain-fed barley significantlyincreased straw yield and straw protein content. No significant increase in grainyield or in grain protein content was measured. It was also determined that a statisticalsignificant decrease in the thousand grain weight occurs as biosolids loading rates increasedwith a p-value < 0.000001. This has negative effects on barley’s grain quality.No significant increase in heavy metals in the crop or the soil was observed in thebiosolids treated plots. However, increases in soil organic carbon, total Kjeldahl nitrogenand salt concentrations were increased with increasing biosolids loading rates. The null hypothesis tested in this study showed that applying biosolids to soils plantedwith rain-fed barley had positive effects on the crop with no effects on the soil in comparisonwith no application of biosolids and the application of inorganic fertilizer.