The Effect of Composts on the Production of the Dry Matter In Maize.

The use of organic compost as fertilizer in maize crops is used by growers in Brazil. The objectives of this study were to evaluate the effect of two different organic sources on the dry matter (DM) of maize plants. The experiment was conducted under greenhouse conditions.  Two organic composts were used: Campestre (with inoculants) and normal (without inoculants). A randomized complete block design was used with six rates of each compost (0, 5, 10, 20, 40, and 80 t ha^-1) and 4 replications. Compost was incorporated separately into 5 kg of Oxisol with medium texture (red latosol). Seeds of maize hybrid BR-106 were planted on July 8, 2008, and harvested on August 11, 2008. Plant dry matter and leaf nitrogen concentration were measured and correlated. Our results showed DM yield of maize plants increased with rates up to 20 t ha^-1 for the Campestre compost and 10 t ha^-1for normal compost, with means of 4.59 g and 3.58 g pot^-1, respectively. However, N concentration of the leaves was greater when lower doses of compost were used, averaging 42.70 and 38.15 g kg^-1 in the control, compared to 12.08 and 13.04 g kg^-1 at 80 t ha^-1, for Campestre and normal compost, respectively. Leaf N concentration for both composts was greatest at a rate of 20 t ha^-1 and declined at higher rates. Campestre compost application led to higher leaf N concentrations than normal compost. Our study indicates that Campestre compost was more efficient than normal compost for maize dry matter production.