Soil heterogeneity is a natural feature of plant growth environment, and a large range of its variability can be observed at the distance scale of the range of a single plant root system. That type of variability of soil properties occurs in the field as a result of natural processes and cultivation. The range of variability of soil properties can be increased by localized fertilizer placement advised in maize cultivation.

The aim of the studies was to evaluate the impact of localized soil fertilization and compaction within maize root system on shoot and root growth and on the uptake of water and minerals.

Split root experiment on maize growing for 45 days in controlled environment was conducted. Parts of one plant root system were growing in soil columns 45 cm high and 20 cm in diameter. Soil conditions during the experiment were aimed to reflect soil compacted by agriculture machinery traffic and with start fertilization performed into soil of different density (loose, moderately and heavily compacted). The system for maintaining constant soil water potential, at a level optimum for plant growth level and allowing for monitoring plant water uptake by parts of the split maize root system was used.

Within the range of soil density corresponding to loose, moderately and heavily compacted top soil layer, irrespectively of fertilizer placement the increase of soil compaction was accompanied by general decrease of plant biomass. Higher plant shoot biomass of studied objects shows, that under heterogeneous soil compaction, better plant growth conditions occurs when minerals are placed into loose soil. Localized fertilization of uniformly compacted soil leads to more intense root growth in soil enriched with minerals. The effect was the strongest in loose soil and was decreasing with increase of soil density. Localized fertilization of heavily compacted soil was less effective, however it slightly decreased the negative effects of soil compaction. The roots were longer, root length distribution with depth was modified and the contribution of thin roots was higher in fertilized part of heavily compacted soil as compared to the unfertilized half of the soil column.

The main factor limiting root water uptake from heavily compacted soil was increased soil mechanical resistance limiting root length. Shorter roots in heavily compacted soil had greater water uptake efficiency as compared to loose and moderately compacted soil although it did not compensate the root shortening resulting from increased soil resistance.

Increased soil mechanical resistance to root growth in top soil of heterogeneously compacted soil resulted in increased root growth in looser soil beneath the compacted layers. Similar root length distribution was observed in the second part of a single plant split root system even if it was growing in looser soil. Both parts of a split root system of which at least one part was growing in compacted soil had shortened thin roots irrespectively of soil compaction and the depth. This indicates a negative effect of compacted soil in which a part of the root system grows, on roots growing in looser soil.

The comparison of root growth in columns with localized or uniform fertilization with the same dose of minerals allowed to conclude that roots grow faster with increase of fertilized soil volume than with increase of minerals concentration.

Compensatory water uptake by roots from looser soil was achieved mostly by more intense root growth in a soil with better growth conditions than unitary water uptake increase.

The results show that the growth and structure of root system are dependet on the state of soil compaction and fertilizer placement. Heterogeneous soil compaction and fertilization within a root system of one plant affects uptake of water and minerals depending on the interplay of these factors. The differences in the growth and water uptake by parts of a split root system growing in such a heterogeneous environment showed that the use of average values may be misleading.