Results of long-term trials on the direct drilling of maize in Hungary

In Hungary trials on direct drilling started 35 years ago in 1962. Experime nts on maize have been carried out since 1977 in the experimental field of the Institute of Crop Production of Godollo University on a Ramann's brown forest soil. This report covers two 5-year periods from 1977-1981 and 1992- 1996. The impacts of tillage methods and fertilization on the soil conditio ns, weed infestation and yield were studied. An additional research objecti ve in the first 5-year period was to compare direct drilling with the conve ntional autumn method (ploughing) and with reduced tillage methods (such as strip rotavatoring, rotavatoring and disking) carried out in spring. This experiment has been continued since 1992 to compare direct drilling with co nventional (ploughing), reduced (disking) and soil ameliorating (loosening combined with surface tillage) tillage methods. Three levels of fertilizati on were tested (0, low and optimal). The soil condition required by maize can be characterized by a dry bulk den sity of 1.15-1.35 g . cm(-3) in the seedbed and of 1.35 g cm(-3) at a depth of 10-40 cm. The soil condition influenced by tillage can not be considered as a yield-d ecreasing Factor even at the end of the first five-year period. At the begi nning of the second period the soil was compacted below the ploughed treatm ent and the development of a compacted layer below the depth of disking and below the seedbed of the direct drilling treatment. In the first experimen tal period the order of factors promoting weed infestation was as follows: 1. lack of fertilization; 2. undisturbed soil condition (direct drilling); 3. shallow primary tillage in spring; 4. cropping without rotation; 5. dire ct drilling and/or shallow tillage applied long-term; 6. spring ploughing, while in the second period the main factors in weed infestation, including cover by annual, perennial, grassy and summer weeds, were the omission of f ertilization, rotation and tillage. However, perennial weed infestation was decreased by regular loosening. Factors leading to a reduction in weed inf estation showed the same order in both experimental periods: 1. optimal lev el of fertilization; 2. crop rotation; 3. loosening repeated every year, 4. autumn ploughing. In the first period autumn ploughing resulted in extreme ly high yields. However, significant differences in yield were found betwee n direct drilling and spring cultivations at all fertilization levels. In t he second period the soil conditions influenced by tillage gave significant differences in yield. The order of soil conditions with regard to yield fo llows an upward trend for seed bed depth of 10-16 cm < 0-22 cm < 0-35 cm, a s provided by direct drilling, disking, ploughing and loosening variants.