Browse on keywords: fertility nitrogen soil pH
Search results on 04/23/18
3117. Rasmussen, P.E.. 1989. unpublished data on soil pH from long-term plots at Pendleton, OR. Columbia Basin Agr. Res. Center, P.O. Box 370, Pendleton, OR 97801.
Plots have received various tillage and fertility treatments since 1931. The original pH (1:2 water) was 6.3. Addition of 10 T/ac manure every other year raised the pH to 6.9, while addition of 1 T/ac pea vines raised it to 6.5. Fall burn lowered the pH to 6.2. The decline in soil pH was essentially linear with increasing total N fertilizer added over the years. A nearby permanent pasture had a pH of 7.3.
4002. Mahler, R.L., A.R. Halvorson and F.E. Koehler. 1985. Long-term acidification of farmland in northern Idaho and eastern. Comm. Soil Sci. Plant Anal. 16:83-95.
Soil acidification from N fertilizer first noticed in 1960's; has accelerated since then; critical levels for crops: alfalfa 5.6, wheat 5.2, peas and lentils 5.4; current wheat varieties relatively acid intolerant; liming needed to grow alfalfa on 45% of northern ID fields; acidification may be shifting weed pressures, encouraging diseases, decreasing availability of P and Mo. T: map of pH changes, N fertilizer use.
6001. Russell, J.S. and C.H. Williams. 1982. Biogeochemical interactions of carbon, nitrogen, sulfur, and phosphorus in Australian agroecosystems.. IN: J.R. Freney and I.E. Galbally (eds.). Cycling of C,N,S, and P in terrestrial/aquatic ecosystems..
An excellent review article looking at nutrient cycling and gains and losses over time under different agricultural management. Estimates that over 3 million tons C are tied up in soil organic matter additions each year in Australian farmland. SOM levels are higher now than the native condition under systems that have used a legume pasture in the rotation. There was a generally downward trend in the soil C:N over the first 25 yr of OM accumulation. A WWPP rotation slightly increased SOM, while WWWP decreased it slightly, and fallow systems decreased it significantly. Increases in SOM increased the water-stable aggregates in the soil and improved infiltration. Leguminous pastures had an acidifying effect on the underlying soil.
8744. Mahler, R.L.. 1990. personal communication. Dept. Plant, Soil, Ent. Sci., Univ. Idaho, Moscow, ID 83843.
The theoretical need of wheat grain is 1.35 lb N/bu. In the 18-26" rainfall zone, it typically takes about 2.7 lb N/bu, a fertilizer use efficiency (FUE) of 50%. In the <16" rainfall zone, the actual need is about 2.2 lb N/ac. There is no soil test correlation work for eastern WA dryland areas. Low yield sites should probably get 25% of the fertilizer that the high yield sites get. Anhydrous ammonia will probably disappear from the market as a fertilizer N source, leaving urea as the primary source. Much current work uses urea. There is no difference in wheat yield due to fertilizer form or placement. Deep placement is not necessary in the higher rainfall areas. Slow release fertilizers will become more prevalent. They are more expensive, but can raise FUE to 70%. There is currently an economic penalty on legumes, especially lentils (due to high price), due to low soil pH. There is some lime response on wheat at pH <5.1, probably due to disease and weed effects, and not to toxicity or nutrient problems. Liming materials are available from Addy, WA (MgO material) and the Nez Perce tribe (lime deposit). Tim Murray has data on the effect of low pH on wheat diseases. Current research at UI includes plots on a forest and prairie soil catena, examining optimum fertilization at different landscape positions.