Dryland Winter Wheat Yield, Grain Protein, and Soil Nitrogen Responses to Fertilizer and Biosolids Applications

Table 1

Crop year precipitation and preplant soil test information for each site-year. Plant-available soil moisture is calculated by the commercial testing lab from gravimetric moisture content, an assumed bulk density of 1.2 g cm⁻³ for silt loam soil textures, and an assumed permanent wilting point moisture content of 11% by volume.

Location^†	Year	Sept 1 to Aug 31 crop year precipitation	Plant-available moisture	Residual N	Organic matter	pH	NaHCO3-extractable P^‡	NaHCO3-extractable K	Water-extractable SO4^§
		(mm)	(cm 1.5-m^−1)	(kg ha^−1)	(g kg^−1)		(mg kg^−1)	(mg kg^−1)	(kg S ha^−1)
Lind	2006	304	5.5 (0.3)	141 (22)^¶	8 (1.0)	7.5 (0.1)	6 (0.6)	524 (31)	16 (3.2)
	2007	229	2.5 (0.4)	189 (17)	11 (0.7)	6.8 (0.1)	17 (3.2)	469 (10)	12 (1.5)
Davenport	2006	336	8.5 (0.7)	156 (41)	31 (3.2)	6.7 (0.5)	12 (0.6)	437 (49)	9 (0.6)
	2007	196	8.5	113	24	5.6	20	416	7
Pullman	2006	452	3.9	70	23	5.5	28	281	11
	2007	510	6.4	76	30	5.8	26	266	8

^†Soil series and taxonomic names.
Lind: Shano silt loam—coarse-silty, mixed, mesic, superactive Xeric Haplocambid (both years).
Davenport: Mondovi silt loam—coarse-silty, mixed, mesic, superactive Cumulic Haploxeroll (2006-07).
Hanning silt loam—fine-silty, mixed, mesic, superactive Pachic Argixeroll (2007-08).
Pullman: Palouse silt loam—fine-silty, mixed, superactive Pachic Ultic Haploxeroll (both years).
^‡Critical values for sufficient soil test P (bicarbonate method) are >16 mg kg⁻¹ [9].
^§Critical values for sufficient soil test S are >22 to 34 kg ha⁻¹ [9].
^¶Mean (standard deviation) of three replicate samples. If no standard deviation is indicated then only one, 5-point composite was collected from the study area.