The effect of fertilization and soil cultivation on the yield of maize (Zea mays L.)

The effect of crop production factors on the maize yield was studied on a c hernozem soil with lime deposits at the Latokep Experimental Farm of the De partment of Land Use of the Debrecen Agricultural University between 1989 a nd 1994. A multifactorial long-term experiment made it possible to evaluate the effects and interactions of fertilization and soil cultivation. Soil c ultivation can only be considered to be up-to-date and adaptable if it is a djusted both to soil status and to farming conditions. The method, tool and depth of cultivation must be chosen to suit the physical state of the soil . A consideration of the moisture content of the soil reduces damage to the soil structure. The experimental results prove that on a chernozem soil, provided precipita tion supplies are at least average, winter ploughing, even without fertiliz ation or with low fertilizer rates, causes a substantial increase in the ma ize yield by making the soil nutrients available to the plant. The extra yi eld achieved with winter ploughing without fertilization was 1.4-2.3 t/ha c ompared to the unploughed variant. In fertilized treatments the yield incre ase was greater, averaging 2.8-3.3 t/ha. Over a six-year average, the yield s were 0.6 t/ha lower after spring ploughing than after winter ploughing. In dry years the yield difference was somewhat smaller, but under favourabl e rainfall conditions maize grown after spring ploughing yielded 1.0-1.4 t/ ha less than after winter ploughing. Fertilization was able to compensate i n part, but not entirely, for other unfavourable agrotechnical effects. Wit hout ploughing the extra yield due to fertilization was 2.8 t/ha in dry yea rs and 3.8 t/ha under more favourable rainfall conditions. After winter plo ughing the difference between the years was smaller (0.6 t/ha), with an ext ra yield of 3.1 t/ha in dry years and 3.7 t/ha after average rainfall. The yield-increasing effect of fertilization, averaged over the six years exami ned, differed in the three soil cultivation variants. Linear and quadratic terms were significant in the fertilizer effect, so the relationship can be described well using an optimum curve. The breakdown of the interaction be tween fertilization and soil cultivation using orthogonal polynomes indicat es that in the linear phase, representing initial low fertilizer rates, the re is no substantial difference of the three types of soil cultivation.