REPORT ON THE EFFECT OF THE SOILMIX MACHINE ON ROOT DISTRIBUTION OF VINES

UNIVERSITY OF STELLENBOSCH

E. Archer & A. Schloms, Department of Viticulture and Oenology,  

 

Root studies to evaluate the effect of the Soilmix machine on vine root distribution and density were done during April 2001 on Kanonkop Wine Estate in the Stellenbosch district. Two vineyards, one of nine months old and another of 15 months old were used in this study. The soil preparation in both cases were partially done with the Soilmix machine and partially with a shift delve plough. Several root study pits were dug to establish a pattern of differences and the most typical profile walls were used for photographs.

The attached figures show that in both cases a vastly improved root colonisation was obtained in the soil prepared by the Soilmix machine. The root number figures in Table 1 show at root distribution and density of roots were improved by the Soilmix machine, both in the cases of 9 month old and 15 month old vineyards. Especially in the case of the fine root density (as an indication of the quality of the root system) marked improvement was caused by the Soilmix machine. It is also clear that this improved root development resulted in noticeably stronger top growth than was the case with normal shift delving. The Soilmix machine created a homogeneous rooting medium (also clearly visible in the homogeneous color of the soil in the figures) which not only is advantageous for root colonisation, but also resulted in vine plants that are better buffered against unfavourable climatic conditions such as heat waves in February. This is achieved by creating a bigger soil water reservoir and a larger root-soil contact surface. This is advantageous for grape quality, not only because of lesser stress during ripening, but also importantly, for the production of hormones regulating the growth and ripening processes. Hormone synthesis takes place in the root tips and, as can be seen from the figures, the number of root tips are greatly increased by the Soilmix machine.

 TABLE 1       The effect of the Soilmix machine on the number of fine (‹ 2mm diameter) and thick (› 2mm diameter) roots per m² profile wall.

Method of soil preparation	Number of roots / m2 profile wall
	9 month old vineyard		15 month old vineyard
	‹ 2mm	› 2mm	‹ 2mm	› 2mm
Traditional deep delving	107	9	136	12
Soilmix machine	302	13	513	27

  

The Soilmix machine also will have an important application in existing vineyards where soil compaction frequently affects vine performance detrimentally. Its ability to work deep in relatively narrow rows has very important application potential in South African vineyards. The root pruning thus obtained will rejuvenise vineyard performances in cases where soil compaction is responsible for vine decline. For the first time it is now possible to rectify bad soil preparation in existing vineyards.

This machine also has wide application in other long term crops such as deciduous fruits and citrus, not only for soil preparation, but also for in-orchard cultivation. It is without doubt a breakthrough in improving root growth conditions which can only improve the performance of permanent crops on a wide range of soil types.