Accumulation of macronutrients by weed and corn in coexistence in soil with different fertility managements

The understanding of weed interference on crops is very important in agricultural systems. However, there is little known about the influence of soil fertility management in competitive relations between plants. The objective of this study was to evaluate the effects of mutual interference between weeds and corn on the content of macronutrients under different soil fertility managements. The experimental test was conducted in a greenhouse, considering four soil fertility managements (with calcium and magnesium silicate and fertilization; with limestone and fertilization; without correction of acidity, but with fertilization; without correction of acidity and without fertilization) and eleven crops (five arrangements of competition between Zea mays and the weeds Urochloa brizantha, Ipomoea grandifolia, Conyza canadensis, Hyptis suaveolens and Bidens pilosa, plus the six species in monoculture). Corn had reductions exceeding 50% in the content of all macronutrients under interference of U. brizantha. Additionally, U. brizantha and B. pilosa in competition with corn has high ability to extract macronutrients in the four soil conditions. Calcium and magnesium silicate and limestone influenced variable on nutrient accumulation by weeds in monoculture or under interference. Corn grown in soil amended with silicate suffered greater competition with weeds compared to grown in soil amended with lime. U. brizantha was the specie most damaging to the crop. B. pilosa showed high potential for nutrient cycling in the four soil fertility management.