The experiment was carried out in the years 2009-2010 in organic farm of Agricultural Experimental Station Grabow (Mazowieckie Voivodeship), by crossed subblock method. Dose of natural fertilization (20 and 40 t composted manure per 1 ha) was the first factor and the second factor - cultivation method: A - control object (without weed control), B - brush weeder (three times during the vegetation season), C - weeding hoe (three times during the season), D - brush weeder (two times during the season) and hiller. In year with bigger amount of rainfall in July, using of brush weeder and hiller allowed to obtain the largest green and dry matter of maize yield. In such moisture conditions, dry matter yield of maize cultivated by mechanic method were higher by about 37% than on control object. Dry matter yields of maize fertilized with dose of 20 t per ha on the objects, without weed-control measures, were less by about 19% than maize fertilized with dose of 40 t per ha. On the objects, where mechanic cultivation were used, differences were less (from 7 to 11%). Content of dry matter in maize plants was a little differentiated both organic fertilization and cultivation method. The increasing of fertilization from 20 to 40 t per ha caused the significant growth of cob share in maize plant. Under conditions of limited amount of rainfall in July, yielding of maize on mechanic cultivated objects were higher by about 55% than on the control object. On the object without weed-control measure, yielding of maize fertilized with dose of 20 t per ha was similar than one fertilized with 40 t per ha. Plants on control objects contained less dry matter (about 7%) in comparison to those cultivated by mechanic measures. Dose of organic fertilization was a little influence on plants structure. Independently on whether conditions in vegetation period, share of cobs in plant structure was significantly less on control object, than on one with weed-control measures. The content of dry matter in maize cob was significantly higher than in whole plant. The percentage of seeds in cob maize was less by about 20% on control object than in mechanic cultivated. Measures limited occurrence of weeds and dose of organic fertilization were relatively a little influence on forming of maize cob structure.