Browse on keywords: soil quality Pacific Northwest
Search results on 05/21/13
261. Allmaras, R.R., K. Ward, C.L. Douglas and L.G. Ekin.. 1982. Long-term cultivation effects on hydraulic properties of a Walla Walla silt loam.. Soil Tillage Research, 2:265-279.
Hydraulic properties were significantly changed by 50 years of wheat-pea and/or wheat-fallow rotations. pH was reduced, dry bulk density was increased, more smaller soil pores were produced at the expense of larger pores, in the upper 30 cm soil hydraulic conductivity was reduced 10-fold increasing water runoff and denitrification.
1688. Douglas, C.L.. 1983. Silicic acid and oxidizable carbon movement in a Walla Walla silt loam.. Ph.D Thesis, Oregon State Univ., Corvallis, OR. 75pp..
This study shows that use of ammonia fertilizers over the past 40 yrs, and particularly anhydrous ammonia in the past 15, has resulted in a more acid plow layer. The decrease in pH has caused soluble silica to leach out of the plow layer and led to cementation of the plow pan layer below 15 cm. The result is reduced water infiltration, increased water runoff and soil erosion, and increased soil water evaporation. Corrective applications of hydrated lime are explored. T: Mean silicic acid concentration in leachates from 15 cm soil layers as affected by long term N treatments. Long-term N and residue management effects on soluble carbon movement in four 15 cm layers. Soil pH and carbon addition effects on silicic acid concentration and transfer from the 0-15 cm layer.
5649. Rasmussen, P.E. and C.R. Rohde. 1988. Long-term tillage and nitrogen fertilization effects on organic nitrogen and carbon in a semi-arid soil.. Soil Sci. Soc. Am. J. 52(4): 1114-1117.
A 44 year experiment of wheat-fallow rotations in the Pacific Northwest. Main treatments were 3 primary tillage systems, one conventional and two stubble mulch. Subplots were 6 different N treatments. Organic N and C in the top 75mm of soil were 26 and 32% greater in the stubble mulch systems than the conventional system. Stubble mulch plots contained 245 kg more N/ha than the conventional plots. In all treatments 18% of applied N was incorporated into the organic fraction. N transformations were the same for stubble and conventional treatments. T: Organic N and C at different depths as effected by tillage method and N fertilization. Tillage and N effects on organic N in upper 225 mm of soil. Tillage and N effects on organic C in upper 225 mm of soil.
5659. Rasmussen, P.E. and C.R. Rohde. 1989. Soil acidification from ammonium-nitrogen fertilization in moldboard plow and stubble-mulch wheat-fallow tillage.. Soil Sci. Soc. Am. J. 53(1):119-122..
Change in soil pH in relation to applied N was determined for one conventional and two stubble-mulch tillage treatments. Acidifying effects were concentrated in the top 7 cm of the stubble-mulched soil, but distributed to 22 cm or more with moldboard plowing. The rate of pH decline was greater for moldboard plowing than stubble-mulching. T: Long-term N fertilization effect on pH in the upper 45 cm of soil under different tillage systems. Linear relationship between applied N and soil pH, as affected by tillage.
5684. Rasmussen, P.E. and R.R. Allmaras. 1986. Sulfur fertilization effects on winter wheat yield and extractable sulfur in semiarid soils.. Agronomy J. 78: 421-425.
Wheat yield in response to S was affected by yield level, intesity of cropping, and S accumulation in calcic horizons. At noncalcareous wheat-fallow sites with little S accumulation within 1.8 m of the surface, progressive downward movement of S occurred over 4 yrs. At an annual crop site with a calcic horizon, substantial yield responses to residual S occurred 25 yrs after application of 270-1570 kg S/ha. The highest fertilizer use efficiency was by fertilizing every 2nd crop with 14 kg S/ha when soil tests and yield data indicate a S deficiency. T: S and N fertilization effects on grain yield and S uptake by winter wheat. Extractable S in the upper 0.6 m of soil 2 and 4 yrs after S application. Cumulative plant uptake and extractable S in soil 1 and 4 yrs after S application. Extractable S in soil profile 25 yrs after S application ceased. Wheat yield response 1960-75, as affected by S applied between 1931-50.
5744. Rasmussen, P.E., R.E. Ramig, R.R. Allmaras and C.M. Smith.. 1975. Nitrogen - sulfur relations in soft white winter wheat. II. Initial and residual effects of sulfur application on nutrient uptake and N/S ratio.. Agronomy J. 67(2):224-228.
This study determined S and N uptake and distribution in soft white winter wheat fertilized with S in combination with deficient, optimum, and excessive N. Residual uptake from 17, 34, and 68 kg of applied S/ha was evaluated in 3 subsequent wheat crops receiving optimum N fertilization. S uptake and concentration in the first crop was proportional to the rate applied, but accumulated primarily in vegetative tissue when present in excess of the amount required for grain protein. Uptake from residual S was lower than from applied S. Grain yield responses to S were poorly correlated with S concentration or N/S ratios in tissue, because of inconsistancy of S accumulation in plant parts and the dominant effect of N on yield. T: Effect of N and S fertilization on S concentration and uptake at 3 stages of growth in a first wheat crop. Effect of residual S on grain yield and S concentration in grain and straw of second, third, and fourth crops. Relationship between S concentration in mature whole plants and grain yield receiving optimum N fertilization.
7057. Van Doren, G.S.. 1983. The form and distribution of soil phosphorus as affected by management and soil variability.. M.S. Thesis, Dept. of Agronomy and Soils, WSU, Pullman, WA.
Studies were initiated in the Pacific Northwest to determine long-term effects of cropping systems and tillage management practices on the form and distribution of soil phosphorus. Studies indicated that, in comparison with the native Palouse prairie, organic phosphorus in Palouse soils has declined more than 50% with cultivation and cropping. Stratification of phosphorus, with increasing concentration towards the soil surface, was found in no-till soil. A cropped soil which has been managed without utilizing chemical fertilizer showed total and organic phosphorus accumulations in the upper 30 cm of the soil profile with depletions lower in the profile. This was not evident in the adjacent, conventionally farmed soil. However, soil varibility often masked the effects of soil and crop management on phosphorus forms and distribution in soil. For example, soil series induced wider variation (significant at the 0.01 level) in phosphorus values than did management in a study which included detailed soil mapping. This study demonstrated that many experiments are not designed to quantify variations in soils; in fact, some are designed to mask soil differences by statictical analysis. Sequential testing is suggested as an appropriate experimental design to quantify soil variability.