Die Bodenkultur - Journal for Land Management, Food and Environment
M. Birkás and Cs. Gyuricza
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. Experiments on maize have been carried out since 1977 in the experimental field of the Institute of Crop Production of Gödöllö University on a Ramann's brown farest soil.
This report covers two 5-year periods from 1977-1981 and 1992-1996. The impacts of tillage methods and fertilization on the soil conditions, weed infestation and yield were studied. An additional research objective in the first 5-year period was to compare direct drilling with the conventional 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 conventional (ploughing), reduced (disking) and soil ameliorating (loosening combined with surface tillage) tillage methods. Three levels of fertilization were tested (0, low and optimal).
The soil condition required by maize can be characterized by a dry bulk density 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-decreasing factor even at the end of the first five-year period. At the beginning of the second period the soil was compacted below the ploughed treatment and the development of a compacted layer below the depth of disking and below the seedbed of the direct drilling treatment.
In the first experimental 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. direct 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 fertilization, rotation and tillage. However, perennial weed infestation was decreased by regular loosening.
Factors leading to a reduction in weed infestation showed the same order in both experimental periods:
1. optimal level of fertilization;
2. crop rotation;
3. loosening repeated every year,
4. autumn ploughing.
In the first period autumn ploughing resulted in extremely high yields. However, significant differences in yield were found between direct drilling and spring cultivations at all fertilization levels. In the second period the soil conditions influenced by tillage gave significant differences in yield. The order of soil conditions with regard to yield follows an upward trend for seed bed depth of 10-16 cm < 0-22 cm < 0-35 cm, as provided by direct drilling, disking, ploughing and loosening variants.
Key words: direct drilling, maize, weeds, soil condition, yield.