Browse on keywords: organic matter Pacific Northwest
Search results on 05/18/13
1710. Douglas, C.L., P.E. Rasmussen, L.L. Baarstad and R.R. Allmaras. 1984. Crop residue distribution by combines.. OR Agr. Expt. Sta. Special Report 713, p. 37-40.
Uniform distribution of wheat straw and chaff is necessary for success of conservation tillage programs. Results indicate that: a)standard factory-produced combines distributed straw and chaff unevenly in the field; b)straw-choppers did not automatically improve uniformity of distribution; c)a chaff spreading attatchment on a cylinder-type combine improved distribution significantly; and d)shop modification of flails on a rotary-type combine gave a nearly uniform distribution. Improvements on combines are seriously needed to assure the uniform straw and chaff distribution so necessary for successful adoption of conservation tillage systems. T: Straw distribution by cylinder and rotary combines.
1720. Douglas, C.L., R.E. Ramig, P.E. Rasmussen and D.E. Wilkins. 1987. Residue management: small grains in the Pacific Northwest.. Crops and Soils Magazine, Aug./Sept., p.22-24.
Lack of water usually limits production in dryland cropping areas of the inland Pacific Northwest (WA, OR, ID). Precipitation is frequently insufficient during the growing season; thus, it is necessary to rely on stored soil water for cropping. Annual precipitation is unevenly distributed with approximately 65% occurring between November and March when soils may be frozen. Conventional tillage systems in the steeply rolling areas of Idaho, eastern Wash. and eastern Oregon result in high soil erosion rates which will eventually make it impossible to sustain high levels of crop production. Enough surface residue (normally 1 T/ac) must be left after fall seeding to control winter soil erosion and to sustain current production. Cereal residue management in the Pacific Northwest must begin at harvest of the previous crop. Uniform distribution of residues behind a combine eliminates chaff rows which shelter rodents and weeds, and create physical barriers to herbicide application and cereal growth. Fertilizer banding is necessary to reduce its use by shallow rooted weeds and the immobilization of certain nutrients by microorganisms. Equipment design must allow seeding and fertilizing through large amounts of surface residues.
5632. Ramig, R.E., P.E. Rassmussen, R.R. Allmaras and C.M. Smith.. 1975. Nitrogen - sulfur relations in soft winter wheat. I. Yield response to fertilizer and residual sulfur.. Agronomy J. 67(2):219-223.
This study measured yield response of wheat to S applied with a range of N for the first crop and monitored residual S effects on yields of 3 subsequent crops. Significant N to S relationships were found. The first crop did not respond to S when N was deficient or optimal. Residual S increased straw yield in all crops and grain yield in 1 of 4 trials for the second crop, 3 of 3 trials for the third crop, and 2 of 2 trials for the fourth crop. Wheat response to residual S was influenced by N rates applied to the first wheat crop. High N and S fertilization resulted in early drought and lower yelds. Gradual release of residual S from recent organic matter apparently provided S at a rate adequate for efficient water use and maximum yield. T: Grain and straw yield response to S and N in first through fourth wheat crop following fertilization. The initial and residual effects of S on grain yield of wheat receiving optimum N.
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.
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.