Jacek Rajewski

APPLICATION OF CONSERVATION TILLAGE

IN SUGAR BEET PRODUCTION

Summary 

In contemporary agriculture, the economic and energetic effectiveness is decreasing, and the growing expenditure on plant protection agents and fertilization do not always provide a proportional grow in yield. The most energy-consuming process is tillage, which consumes up to 40% of energy necessary in the process of sugar beet production. Therefore, conservation tillage, which is an energy-saving technology, is becoming more and more significant. All over the world, for many years research has been conducted with focus on this system of sugar beet cultivation and the obtained results, due to various settlement and agrotechnical conditions, are often divergent. However, low energy consumption and workload, along with high yield, result in wider application of conservation tillage. So far, research into this technology of sugar beet conservation in Poland has been carried out in moist areas (Lower Silesia, the Opole region, Western Pomerania, Kuyavia).   

 The aim of the research was:

a)   to learn about the influence of conservation tillage variants – including no-tillage – as well as intensive and extensive level of herbicide protection on soil settlement conditions, weed infestation of the field and growth, yield and technological quality of sugar beet roots; the research was to show which of the applied conservation systems had been the most effective not only from the perspective of the yield, but also its technological value,

b) to test this conservation system under precipitation shortage conditions, i.e. in Eastern Greater Poland.

 The field experiment was conducted on medium textured soil at Plant Breeding Station of Sugar Beet Breeding Company in Straszków near Kłodawa, Wielkopolska Voivodship (52^o 13^’N; 18^o 57^’E) in the years 2004–2007. The forecrop for sugar beet was winter wheat. The research was carried out on the basis of strict dual-factor field experiments conducted as a split-plot method in three replications.

Factor I was the level of herbicide protection. In treatment A (intensive), Roundup 360 SL (glifosat) was applied before sowing. After sowing and sugar beet emergence, the object was sprayed with conventional herbicides twice. In treatment B (extensive), Roundup 360 SL was applied two to four days after sowing and after sugar beet emergency the object was sprayed with herbicides against emerging weeds.

Factor II was the various conservations systems. In treatment 1 (control), conventional tillage after stubble crop with fall ploughing was applied, followed by conventional sowing. In treatment 2, stubble crop in the form of white mustard that fights beet cyst nematode (Heterodera schachtii) was left in the form of mulch until spring. Treatment 3 was characterized by leaving forecrop straw and stubble crop until spring. In treatment 4, forecrop straw was left until spring. Before the sowing of stubble crop (objects 1–3) and in plots with the left-out straw (object 4), a chisel was applied. In treatment 5, where uncovered forecrop straw had been left until spring, no-tillage was applied. In treatments 2–5 (conservation tillage) direct sowing was applied.

            Conservation tillage, when compared to conventional tillage of sugar beet, resulted    in the increase in root weight, length and width. Yield in these cultivation systems (77.2–84.2 t ha^-1) was similar to yield in conventional tillage (81.9 t ha^-1). In no-tillage (straw left until winter and direct sowing), the soil was characterized by the highest moisture (mean value of 12.3% of volume) and the lowest soil compaction (2.67 MPa). The emergence was the weakest here and the final plant stand the smallest. The yield level was 68.0 t ha^-1. No-tillage influenced the increase of deformed roots and roots infested by soil pathogens. In this treatment, beets protruded the most and were the most vulnerable to toppling during harvest. The conservation tillage systems contributed to a significant limitation of weed infestation. Limiting the number of herbicide treatments from three to two did not significantly differentiate secondary infestation or root yields or sugar beet leaves. Conservation tillage had an influence on the decrease in bulk density of soil at the final stage of sugar beet vegetation. Reduced herbicide protection and fertilization of sugar beet with straw and stubble crop left until spring contributed to the increase in the content of organic carbon, available phosphorus and pH in soil in the final phase of vegetation. The best emergence and stand among conservation tillage systems was observed in the field, where beets were cultivated on straw and stubble crop with reduced herbicide protection. The highest sugar content and yield was marked in sugar beet roots cultivated exclusively on stubble crop, while the lowest under the conditions of no-tillage, where an increased content of treacle-producing elements was observed. The highest technological sugar yield (14.0 t ha^-1) was obtained in the conservation tillage system with stubble crop and forecrop straw left until spring and direct sowing with extensive herbicide protection.

            The conservation tillage of sugar beet can be applied under limited precipitation conditions of Eastern Greater Poland.