Comparative Forage Yield of “Poor” Versus “Good” Grass Stands under Different Soil Fertility Regimes in Northeastern Saskatchewan

Abstract

ABSTRACT Forage yield and its response to fertilizers are affected by the condition of forage stands. A field experiment was conducted on a Gray Luvisol (Typic Croyoboralf) soil at Pathlow in northeastern Saskatchewan, from 2004 to 2006, to determine if low forage yields in “poor” grass stands are due to nutrient deficiencies, other soil properties and/or species composition, and to determine if forage dry matter yield (DMY), protein concentration (PC), and protein yield (PY) in these areas could be improved by fertilization. The four fertilizer treatments: no fertilizer—nil, plus three combinations of increasing amounts of nitrogen (N), phosphorus (P), potassium (K), and sulfur (S) fertilizers (i.e., 45 kg N + 10 kg P + 12.5 kg K + 5 kg S ha−1; 90 kg N + 20 kg P + 25 kg K + 10 kg S ha−1; and 135 kg N + 30 kg P + 37.5 kg K + 15 kg S ha−1) were applied annually to the same plots in early spring of 2004 and 2005. The lower forage yield in “poor” compared to “good” grass stand areas was most likely due to differences in plant species composition, although other factors such as soil fertility and compaction may have also contributed to lower DMY. There was a significant response of DMY, PC, and PY to applied N, P, K, and S fertilizers in both “good” and “poor” grass stands in both years. The DMY, PC, and PY in the first year (2004) continued to increase up to the highest fertilizer rate used in this study, but in the second year (2005) there was no increase in total DMY in both grass stands, and in PC and PY in “good” grass stand with application of fertilizer blend beyond the 90 kg N + 20 kg P + 25 kg K + 10 kg S ha−1 rate. Fertilizer application for two years also increased the proportion of smooth bromegrass in both stands, indicating that proper nutrient management may increase the proportion of smooth bromegrass (high yielding grass species) in the “poor” growth area, thereby improving forage yields. Overall, the findings indicate that forage yields and quality in “poor” grass stand areas can be improved considerably by applying fertilizer nutrients that are lacking in the soil. Also, the significant responses observed in the “good” grass stand areas suggest that these regions of the field can also benefit from additional fertilization.