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Soil acidifi cation has become a major environmental challenge for crop production in the inland Pacifi c Northwest (iPNW). We evaluated the eff ects of tillage and N-fertilizer management on soil pH, soil organic carbon (SOC), soil N, and crop yields from 1995 through 2010 in an ongoing long-term experiment in eastern Oregon. Tillage systems included moldboard plow (MP), disk plow (DP), and subsurface sweep (SW) and N-fertilizer rates were 0, 45, 90, 135, 180 kg N ha -1 crop -1 in a dryland winter wheat (Triticum aestivum L.)-summer fallow (WW-SF) system. Soil pH, SOC, and N were monitored in 1995 and 2010, and crop yields were monitored every other year. Soil pH was lower in the higher N rate treatments. Long-term N fertilizer application increased soil acidity in 0-to 10-cm depth by 0.3, 0.2, and 0.3 units in MP, DP, and SW, respectively, for every 1000 kg N applied through ammonical N fertilizers. Soil pH was higher in DP than MP in 10-to 20-and 20-to 30-cm depth profi les. Th e SOC and N concentrations in the top 30-cm depth were lower in 2010 than in 1995 across all treatments. Wheat yield increased signifi cantly with increase in N rates from 0 to 90 kg N ha -1 crop -1 . Th ere were no further yield increases above 90 kg N ha -1 crop -1 . Soil acidifi cation, SOC and nutrient dynamics should be carefully monitored in cropping systems using ammonical N fertilizers, particularly under high rate of N application and reduced tillage.

Farmers' knowledge on pesticides and their safe use are critical for implementing effective pest management program. A household survey was conducted using the semi-structured questionnaire to evaluate vegetable growers' knowledge on pesticide safety and pest management practices in Nepal. Results indicated that chemical pesticides were the primary choice of over 80% growers for pest management. Notably, 90% growers were aware of adverse effects of pesticides on human health and to the environment. Over 84% growers used at least one form of personal protection equipment (PPE) during pesticide spray or handling, although the quality and appropriateness of the PPE warrants further investigation. Nearly 17% growers received at least one short-term training on integrated pest management (IPM); however, all of them neither knew the harmful effects of pesticide residues nor practiced proper pesticide disposal methods. Over 90% of growers rely on local pesticide retailers (i.e., Agro-vets) for technical know-how about pesticide selection, handling, and use. This study highlighted a need for immediate implementation of strict pesticide use regulations and recommended educational programs for pest control professionals, growers, and pesticide retailers.

Roots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestration, but information on root biomass of bioenergy perennial grasses is lacking. Root/shoot ratios are used to estimate crop root biomass and C inputs, but the values for perennial grasses are also scanty. We examined root biomass, root/shoot ratios, and soil water contents to a depth of 120 cm after grass harvest in the fall for three bioenergy perennial grasses applied with four nitrogen (N) fertilization rates from 2011 to 2013 in the northern Great Plains, USA. Perennial grasses were intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth and Dewey), smooth bromegrass (Bromus inermis L.), and switchgrass (Panicum virgatum L.), and N fertilization rates were 0, 28, 56, and 84 kg N ha−1. Root biomass declined with depth and about 60% of the total biomass was located at 0-15 cm where intermediate wheatgrass and switchgrass had higher biomass than smooth bromegrass in 2011. Shoot biomass was greater in intermediate wheatgrass in 2011 and in switchgrass in 2013 than other grasses and increased with increased N rates. Root/shoot ratio was greater in switchgrass than other grasses at 0-120 cm in 2011, but was greater in smooth bromegrass than switchgrass at 0-60, 0-90, and 0-120 cm in 2012 and 2013. Mean root/shoot ratios across N rates and years were not different among grasses and varied from 1.54 at 0-15 cm to 2.54 at 0-120 cm, which were substantially greater than 0.15 and 0.33, respectively, observed for spring wheat (Triticum aestivum L.). Soil water content increased with depth and was greater under switchgrass than other grasses at 0-120 cm in 2011 and 2013. Water content varied with N rate at various soil depths and years. Root biomass was negatively correlated with soil water content (r = −0.56, P = 0.03, n = 15). Because of greater root and shoot biomass, intermediate wheatgrass reduced soil water content due to increased water uptake and will likely provide more C inputs for soil C sequestration from belowground biomass compared to smooth bromegrass and spring wheat. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. A B S T R A C TRoots help in soil water and nutrient uptake and provide carbon (C) input for soil C sequestration, but information on root biomass of bioenergy perennial grasses is lacking. Root/shoot ratios are used to estimate crop root biomass and C inputs, but the values for perennial grasses are also scanty. We examined root biomass, root/ shoot ratios, and soil water contents to a depth of 120 cm after grass harvest in the fall for three bioenergy perennial grasses applied with four nitrogen ( . Root biomass declined with depth and about 60% of the total biomass was located at 0-15 cm where intermediate wheatgrass and switchgrass had higher biomass than smooth bromegrass in 2011. Shoot biomass was greater in intermediate wheatgrass in 2011 and in swi...