Browse on keywords: weed pH
Search results on 05/21/13
2862. Hurd-Karrer, A.M.. 1946. Relation of soil reaction to toxicity and persistence of some herbicides in greenhouse plots. USDA Technical Bulletin 911.
Deals with herbicides used prior to 2,4-D, such as sodium chlorate, sodium thiocyanate, ammonium sulfamate, borax. Initially, all herbicides were most toxic in acid soils, and least toxic in alkaline soils, and persisitence was similar. Borax was the most persistent. Nitrogen fertilizer did not reduce chlorate toxicity in a practical manner.
3945. Mahler, R.L.. 1981. Implications of acidification of farmland in northern Idaho.. ID Agr. Expt. Sta. CIS #629.
Loss of Ca and Mg is primarily by crop removal in northern Idaho; wheat crop removes 20-50 lb/ac/yr of each cation; ammonium-based fertilizers have been main acidifying factor; had been a big change in past 25 yrs; large % of soils now below pH 6.0; current wheat varieties in Idaho acid intolerant; soil acidity may favor certain weeds and diseases.