Leached Chernozem Soil Research Articles

Comparative evaluation of early potato varieties and the mid-season variety Zlatka and ways to improve their seed production efficiency in the forest-steppe of Priobye

The paper provides data on the comparative assessment of early potato varieties on two main soil types in the forest-steppe of Priobye. The experiments were conducted from 2020 to 2022 in the Novosibirsk District of the Novosibirsk Region on leached chernozem soil at the "Praktik" Experimental Farm (a division of Novosibirsk SAU) and on grey forest heavy loamy soil at CJSC agricultural enterprise "Michurinets." The research aimed to study the efficiency of using the modern gene pool of early potato varieties and to explore ways to improve their virus-free seed production. The study achieved high potato variety yields in conditions of leached chernozem soil ("Praktik") and grey forest heavy loamy soil (CJSC agricultural enterprise "Michurinets") located in the northern forest-steppe of the Novosibirsk Priobye. Leached chernozem on experimental plots had a humus content of 6.76%, gross nitrogen of 0.24%, phosphorus of 0.21%, and potassium 1.25%. The concentration of quickly hydrolysable nitrogen was 12.3, mobile phosphorus was 25.2, and exchangeable potassium was 12 mg/100 g of soil, with a pH of 5.89. Grey forest soil contained 3.8% humus with a pH of 5.53; Nitrate nitrogen of about 10 mg/kg; mobile phosphorus of 12.8 mg/100 g; Exchangeable potassium of 9.2 mg/100 g of soil. The research showed that on grey forest soil in open ground conditions, the productivity of early potato varieties was as follows: Red Scarlett - about 32 t/ha, Rozara - 30 t/ha, and the mid-season variety Zlatka - 28 t/ha. It was demonstrated that the seed fraction in the yield dominated these varieties. The authors noted a coefficient of variation of the fractional composition at the level of V=12.6-28%, depending on the array. The highest yield of virus-free tubers was observed in the Terra and Santé varieties. On leached chernozem soil during the study of early types, the minimum productivity was 1024 g/plant for the Rozara variety, 987 g/plant for the Riviera variety, and 986 g/plant for the Kolomba variety, which is significantly higher than the standard (Lyubava variety). It was statistically determined that the yield of early potatoes depended on genotype by 37% and on the year's conditions by 27%.

Soil biogenicity in the rhizosphere of different wheat genotypes under the impact of fertilization treatment

The rhizosphere is a dynamic environment in which many parameters may influence biogenicity. The important factors determining the microbial community in the rhizosphere are plant and soil nutrient supply. The aim of this paper was to determine the abundance of basic microbiological groups in the rhizosphere of four wheat subspecies, in three fertilization treatments in the organic farming system. A field experiment was conducted using a randomized complete block design with four replicates. It was carried out on the leached chernozem soil type. There was significant variability in the abundance of the studied physiological groups of microorganisms between the wheat subspecies, as well as between the fertilization treatments. The rhizosphere of common wheat had the greatest abundance of fungi (24.37 x 103 g-1). The rhizosphere of compactum wheat had the largest abundance of oligonitrophilic bacteria (361.47 x 105 g-1) and amonificators (119.27 x 105 g-1). There were no significant differences in the abundance of actinomycetes between the cultivars of common, compactum and durum wheat, but their lowest number was found in the spelt wheat cultivar (11.25 x 103 g-1). The combined application of biofertilizer and organic fertilizer resulted in a significantly greater abundance of amonificators (56.6%), fungi (28.2%) and oligonitrophiles (14.6%) than in the control treatment. The results show that the crop variety and application of appropriate fertilizer formulations can influence the abundance of the studied groups of microorganisms. This is particularly the case in organic farming, which relies completely on natural resources and processes.

Farklı Temel Toprak İşleme Yöntemlerinin Ayçiçeği Tohumlarının Toprak Katmanındaki Dikey Dağılımına ve Bitki Gelişimine Etkisi

The investigation was carried out on slightly leached chernozem soil type during 2014 – 2016. The effects of different soil tillage methods for sunflower on the vertical distribution of the seeds in the soil layer and the development of the plants were followed – ploughing at 24-26 cm, chisel ploughing at 24-26 cm, disking with disk harrow at 10-12 cm and no-tillage. The highest percent of sunflower seeds in the zone of the soil layer optimal for sowing (5-7 cm) were significantly placed in the areas cultivated with chisel-ploughing (62.1%). Under the other types of soil tillage, their amount decreased. When sowing was performed at a mean diurnal air temperature close to the norm (10.1 °С), the emergence of the plants in the variants with chisel ploughing, disking and no-tillage occurred significantly slower in comparison to ploughing. At higher mean diurnal air temperature (12.0 °С), only at the beginning of sunflower emergence some delay was observed depending on the type of the applied soil tillage. Under these conditions, a significant difference in the occurrence of the phenophases was determined in the variants with disking and direct sowing, as compared to the areas with ploughing. With the minimizing and exclusion of the soil tillage, the growth of the sunflower plants was significantly retarded at the initial stages of their development. At phenophase flowering, the plant height and the stem diameter were lowest in the areas cultivated with disking. The investigated types of soil tillage did not have a significant effect on the diameter of the sunflower heads.

Biological Nitrogen Fixation and Denitrification in Rhizosphere of Potato Plants in Response to the Fertilization and Inoculation

The study aim was to evaluate the potential nitrogen fixation and denitrification in the rhizosphere soil of potato plants, crop yield and output quality in response to the different fertilization systems and the inoculation with Azospirillum brasilense 410. Field stationary experiment was conducted between 2016 and 2019 with potato in a crop rotation system on leached chernozem soil. Farmyard manure, 40 t/ha, applied prior to potatoes planting promotes nitrogen fixation (0.8–2.0 times compared to control). However, it has also affected denitrification (in 1.4–2.2 times higher compared to control). The lowest rate of mineral fertilizers used in the experiment, N40P40K40, was shown as most environmentally feasible. Under its use the increase of soil nitrogenase activity and low denitrification levels were observed. Same trends were also noted for the medium fertilizer rate, N80P80K80. The highest doses of mineral fertilizers, N120P120K120, substantially affected the denitrification process and reduced the nitrogen fixation activity (in 1.9–2.2 times). The combination of manure with the medium fertilizers rate has also resulted in high denitrification levels, while the soil nitrogen fixation activity has restored only at flowering stage. Crop inoculation with A. brasilense combined with the manure application, has not affected studied processes. However, crop inoculation after the green manure intercropping has shown the growth of nitrogenase activity. Used on the mineral fertilizers background inoculation has activated nitrogen fixation and has ensured the decrease of denitrification levels, subject to the fertilization background. High fertilizer rates have hampered the inoculation efficiency. Inoculation has promoted crop yields on unfertilized and mineral backgrounds or following green manure. Crop inoculation following organic and the organo-mineral backgrounds had no significant effect, probably due to the competition for A. brasilense from microorganisms that have created a competitive environment for A. brasilense. Despite its environmental expediency, inoculation combined with the low fertilizer doses underperforms the action of inoculation combined with the medium fertilizer rates showing the latter as the compromise between the environmental requirements and crop productivity. The use of inoculation has promoted the accumulation of starch and ascorbic acid and has contributed to the reduction of nitrate contents in the tubers of inoculated plants.

Effect of different types of soil tillage for sunflower on some soil physical characteristics. Part I: soil moisture

Abstract The investigation was carried out during 2014–2016 in the land of General Toshevo town in the South Dobrudzha region on slightly leached chernozem soil type. The effect of the types of soil tillage for sunflower given bellow was followed: ploughing at 24–26 cm, chisel-plough at 24–26 cm, disking with disk harrow at 10–12 cm and direct sowing (no-tillage) on the soil moisture content. Based on bulk density, wilting point and the determined soil moisture content the plant-available water was calculated. The additional soil tilths of the areas subjected to ploughing, chisel-ploughing and disking with disc harrow included double spring pre-sowing cultivation with harrowing. To destroy the emerging weeds in the variant with direct sowing, a total herbicide was applied. The soil moisture content was evaluated during three main stages of sunflower development: emergence, flowering and technical maturity. The investigated parameter was determined for each of the studied layers – 0–10, 10–20, 20–30, 30–40 and 40–60 cm. In years with normal amounts of rainfalls, no significant differences in the soil moisture under the different ways of soil tillage were observed. Conventional ploughing and tillage without turning of the soil layer contributed to accumulation of more moisture and to higher moisture storage down the soil profile under heavy and intensive rainfalls. Tillage without turning of the soil layer, minimal and no tillage maintained more and better soil moisture in years with limited precipitation and in periods of drought.

Species composition and density of weeds in a grain maize crop depending of soil tillage

Abstract. The study was carried out during 2014-2016 on slightly leached chernozem soil type. The species composition and density of weeds were studied in grain maize grown after previous crop wheat under the following main soil tillage types: ploughing at 24-26 cm, chisel plough at 24-26 cm and no-tillage (direct sowing). The additional tilths of the areas with ploughed and loosened soil included single disking in autumn and double pre-sowing harrowing in spring. A total herbicide was applied for control of the emerging weeds in the variant with direct sowing. The weed control was done according to the standard technology for growing of the crop in this region – treatment with herbicides at stage 3rd-5th leaf of the plants. Weed infestation was read in spring prior to the pre-sowing tillage, immediately before the vegetation treatment with herbicides, and after harvesting. The type of main soil tillage had a statistically significant effect on the species composition and the density of weeds in the grain maize crops grown after previous crop wheat. The use of ploughing, in parallel with the use of chemicals for weed control, decreased the weed infestation in the maize crops. The lower density of weeds under this main soil tillage type was related to changes in the composition and the relative percentage of the respective species in the total infestation. The use of tilths without turning the surface layer and no-tillage in the crop rotation, in spite of the application of herbicides, contributed to the increase of the amount of weeds. The reason for this was the higher variability of weed species typical for shallow tillage types.

Effect of different types of soil tillage for sunflower on some soil physical characteristics. Part II: bulk density and soil temperature

Abstract The investigation was carried out during 2014–2016 in the land of General Toshevo, the South Dobrudzha region of Bulgaria on slightly leached chernozem soil type. The effect of the types of soil tillage for sunflower given bellow was followed: ploughing at 24–26 cm, chisel-plough at 24–26 cm, disking with disk harrow at 10–20 cm and direct sowing (no-tillage) on the bulk density, the moisture content and the temperature of soil. The additional soil tilths of the areas subjected to ploughing, chisel-ploughing and disking with disc harrow included double spring pre-sowing cultivation with harrowing. To destroy the emerging weeds in the variant with direct sowing, a total herbicide was applied. The investigated physical parameters of soil were followed during three main stages of sunflower development: emergence, flowering and technical maturity. The bulk density of soil was determined by soil samples taken from the 0–10, 10–20 and 20–30 cm layers. The soil temperature was read at 800, 1200 and 1600 h to depth 2, 5, 10, 15, 20 and 25 cm with classical soil thermometer. For evaluation of the results dispersion and regression analyses were used. In the slightly leached chernozem soil type, the conventional ploughing leads to lower bulk density in the cultivated soil profile. Under minimal tillage, slight increase of bulk density of the layer underlying the cultivated one was observed over time. The bulk density under tillage without turning of the soil layer and no-tillage was changed and formed primarily under the influence of physical and climatic factors, and under minimal tillage – under the cultivated layer. Under all investigated types of soil tillage, bulk density increased down the soil profile. Replacing ploughing with tillage without turning of the soil layer, minimal and no-tillage lead to decrease of soil temperature. The most significant differences were observed in the 0–10 layer, which, on its part, conditioned accumulation and transfer of thermal energy along the soil profile. The soil temperature decreased with the reduction of the number and depth of the soil tillage operations. The temperature amplitudes between the surface layer and the underlying soil horizons in the areas with ploughing, chisel ploughing minimal and no-tillage were lower. The results concerning the values of the investigated physical properties of soil under different types of soil tillage were statistically significant at different levels of P.

Organic Fertilization of Lucerne and the Following Oat Crop in Non-Irrigated Conditions

Conventional agriculture created ecological and sociological problems worldwide. Practicing organic agriculture need profitable crop such as lucerne, no tillage to destroy the soil structure, usage of natural symbiotic N2 fixation to support nutrition and reduce damages from climatic changes such as droughts and also to supply animals for food. The efficiency of manure fertilization for the production of forage, seeds and root mass after four years of lucerne cultivation was examined in the field experiment,in addition their effect on the following crop such as oat. The trial was performed in the Institute of Forage Crops, Pleven, Bulgaria on leached chernozem soil subtype without irrigation. The well matured cattle manure in the following doses was used: dose 1 - 20.7 t.ha-1 corresponding to 70 kg N. ha-1 (active substance); dose 2 - 41.5 t. ha-1 corresponding to 140 kg N. ha-1 and dose 3 - 62.1 t.ha-1 corresponding to 210 kg N ha-1. It was found that, the highest organic fertilizer use efficiency (153.16) was found in lucerne for forage at a dose of 20.7 t. ha-1. The largest differences in fertilization efficiency depending on the dose were reported in lucerne for forage (1.9 and 2.8 times). The highest efficiency of manure fertilization for root mass accumulation was reported at a dose of 20.7 t. ha-1. The results showed that lower doses of manure can contribute to obtain a high yield of forage, straw, roots and seeds from lucerne. This has a positive effect on grain and straw and also to the following crop such as oat. Organic farming clearly indicated the advantages for both yields and environmentally friendly agriculture and reduction of environmental stresses.

Study of the sliding process of harrow ring working bodies and soil-tillage units in soil

The paper presents of the results theoretical and field study of the ring of a ring roller when it slides across the field at the angle of attack. By calculation, the sliding speed of the roller ring is determined depending on the technical and kinematic parameters of the ring. The analysis showed that the sliding speed of the roller ring depends on the angular velocity of the roller, the diameter of the ring, the angle of attack of the ring and the depth of soil tillage. The sliding speed is also influenced by changes in soil moisture and hardness, its mechanical composition, speed of movement and the shape of the working bodies. Field studies were performed on medium loamy leached chernozem soil of Novosibirsk Region. The experiment was carried out with rings that are used on the Leader tillage units and ring harrows Leader BKM-3.6 and Leader BKS-8. The study was carried out in two periods. The first period was characterized by relative soil moisture of 19.4% and soil density of 1.0 g/cm 3 , the second – by moisture content of 14.0% and density – of 1.35 g/cm3 . The slip coefficient was determined for rings with a diameter of 500, 600 and 700 mm at operating speeds of 2, 2.8 and 3.3 m/s, the angle of attack of the ring was set to 20, 25 and 30 degrees. The most rational parameters of rings for harrows were established: ring diameter – at 600 mm; angle of attack – at 25 degrees; working speed in soil with density of 1.0 and 1.35 g/cm 3 – 3.3 m/s. For tillage machines with rollers with a diameter of 500 mm, it is recommended to set the angle of attack of 20 degrees. The working speed in the soil with density of 1.0 g/cm 3 should be 3.3 m/s, with density of 1.35 g/cm 3 – 2.8 m/s.

Qualitative assessment of souls in technogenic landscapes of Gorlovskiy anthracitous deposit

The paper highlights the results of Morphological studies of soils formed on the outer 30year dumps of overburden and host rocks of the Gorlovskiy deposit and leached chernozem soil. The authors found out that soil covering contains initial, organic accumulative and sod types of embryosimes. Comparative morphological characteristics of soils indicates differences between chernozems and technogenic landscape soils. The results show that soil formation increases concentration of pedogenic organic matter in the soils which is almost equal to that in the black soil. The paper represents qualitative assessment of the soils. The authors calculate the index of specific features which reveals significant differences in the contribution to total variation of different soil properties. The article shows that embryosimes formed on loose sediments are the most fertile. It is established that the level of quality value in rocky soils is determined by concentration of physical clay; in the soils formed on loose rocks it is explained by humus concentration.. The ecosystem is not in a meta-stable climax state; it is developing dynamically, being at the stage of forming sod embryosimes. Therefore, the soil and environmental condition of tailings is satisfactory, as the embryosimes have not been formed after 31 years later the initial phase of technogenesis started. Humus accumulating embryosimes are expected to be formed in the soil covering as well as dry steppe souls on technogenic eluvium and neogenic clays.

Effect of Alfalfa Grown for Forage on Soil Fertility Related to Mineral and Organic Fertilization

The effect of low and high doses of mineral and organic fertilization on the quality of top yield and root mass of alfalfa and effect of mineral and organic fertilization on formation of quality of soil organic matter in dry condition were studied in a field trial. Alfalfa was grown on leached chernozem soil without irrigation at the experimental field of Institute of Forage Crops, Pleven, Bulgaria. The doses of 70, 140 and 210 kg/ha mineral nitrogen (active ingredient) were tested as ammonium nitrate and well-rotted cattle manure. It was found dry mass yield of alfalfa fertilized with manure was to 15.9% higher as compared to dry mass yield obtained from alfalfa fertilized with mineral fertilizer. Sustainable yield index showed the alfalfa crop was more stable under organic fertilization. Alfalfa accumulated to 6027 kg/ha dry root mass for 4-year period of growing. There was from 614 to 1371 kg/ha root mass additional with manure application. Manure treated plants showed higher values for nitrogen in dry root mass/nitrogen in dry aboveground mass ratio and plant available nitrogen. In addition to nitrogen alfalfa add a considerable amount of organic matter to the soil. Humic acids content after mineral fertilization increased to 50.0% as compared to unfertilized control and threefold after manure. Humus content in the soil after manure fertilization was from 10.9 to 41.9% higher as compared to humus content after mineral one.

Effect of mineral and organic fertilization of alfalfa on some seed yield characteristics, root biomass accumulation and soil humus content

A field trial at the Institute of Forage Crops, Pleven, Bulgaria (2000-2003) was conducted to study the effect of mineral and organic fertilization on seed yield of alfalfa, root biomass accumulation and soil humus content. Alfalfa variety 'Victoria' was grown on a leached chernozem soil without irrigation. Rates of 70, 140 and 210 kg ha-1 mineral nitrogen (active ingredient) were tested as ammonium nitrate and well-matured cattle manure. It was found that mineral and manure fertilization at 140 and 210 kg ha-1 increased seed yield by 9.9% and 20.9% for mineral, and by 30.3% and 40.6% for manure. Seed yield was more stable under manure fertilization compared with mineral fertilization. Alfalfa accumulated between 2669 and 3098 kg ha-1 dry root mass after mineral fertilization and between 3310 and 3570 kg ha-1 after manure application. Additional root mass of 482 to 698 kg ha-1 was found to be accumulated for manure treatments compared to mineral fertilization. High ratios of nitrogen yields (192 - 216 kg ha-1) and plant available nitrogen (77 - 86 kg ha-1) have been obtained from the treatments with manure. The highest amount of humus remained in the soil after fertilization of alfalfa with manure at the rate of 210 kg ha-1.

Selectivity of some herbicides to standard wheatgrass (Agropyron desertorum (Fisch.) Schultes) during stand establishment and seed production

A study was conducted in the experimental field of the Institute of Forage Crops - Pleven on a slightly leached chernozem soil in 2011-2012 to determine the selectivity of some herbicides to standard wheatgrass (Agropyron desertorum (Fisch.) Schultes) during stand establishment and its seed production. The study had the following results: the herbicides Kambio SL (320 g/l bentazone + 90 g/l dicamba) - 1250 ml/ha; Kalam (125 g/l tritosulfuron + 600 g/kg dicamba) - 200 g/ha; Lintur 70 WG (4.1% triasulfuron + 65.9% dicamba) - 150 g/ha, and Axial 050?K (50 g/l pinoxaden) - 600 ml/ha showed high selectivity to standard wheatgrass when applied at the stage of 3-4 leaves during the year of stand establishment; the herbicides Imaspro (69 g/l fenoxaprop-P-ethyl+antidote) and Stelar (50 g/l topramezone + 160 g/l dicamba), each applied at the rate of 1000 ml/ha, caused phytotoxicity (scores from 4 to 6), while Termidor (40 g/l nicosulfuron) - 1250 ml/ha completely destroyed the crop (score 9); the herbicides Kambio SL; Kalam; Lintur 70WG and Axial 050?K applied at the same doses at the stage from spring growth to the beginning of shooting up in the seed production year had a high selectivity to standard wheatgrass and could be applied in seed production stands without negative influence on seed productivity. The herbicide Termidor was very phytotoxic (scores from 3 to 7) and prevented the formation of generative stems.

Effects of shepherd's purse (Capsella bursa pastoris (L.) Medic.) on the chemical composition of lucerne (Medicago sativa L.)

A study was conducted in a pure stand of lucerne (variety Viktoria) under natural weed infestation with shepherd's purse (Capsella bursa pastoris (L.) Medic.) on a slightly leached chernozem soil under nonirrigated conditions in the experimental field of the Institute of Forage Crops - Pleven during the 2006-2007 period. The effect of shepherd's purse Capsella bursa pastoris (L.) Medic. on the chemical composition of lucerne Medicago sativa (L.) was analyzed. Statistically significant (P<0.05) functional relations were found between the chemical characteristics and percentage of Capsella bursa pastoris (L.) Medic. participation in the lucerne sward, and forage quality. These relations indicated a multiple practical relevance and a necessity to control Capsella bursa pastoris (L.) Medic. in lucerne stands in order to decrease weed density and improve forage quality.

Effect of cultural practices and fertilizers on sunflower yields in long term experiments

SUMMARY Field experiments were conducted during 1980-2004 at Agricultural Research and Development Institute from Fundulea (Romania) on a leached chernozem soil, well drained, formed on loess, with 33% clay content and 2.8% organic matter in the arable layer. The paper presents aspects regarding the influence of different soil tillage methods (moldboard plow, chisel, paraplow, disking), fertilizers and track by track successive passings of tractor (from 1 to 3) prior to seedbed preparation on sunflower yield under dryland conditions. The developed modern crop production technologies should be improved in response to concerns about environmental impacts of agriculture towards cropping intensification reduction. In this context, choice of a good soil tillage method management is an important decision to improve grain yield and quality. Continuous implementation of optimal rates of fertilizers (from different chemical types or manure) helps us to obtained more efficient sunflower cropping systems. The wheel pressure induces a soil compaction down to 40 cm depth, emphasized by an increase of bulk density and a decrease of total and air porosities below the minimum level needed for normal crop development. The plant height and leaf area were reduced by compaction, as a result of deteriorated soil conditions for root growth. The root biomass was lower by 16- 33% in compacted soil as compared with non-compacted one. RESUMEN Los experimentos en campo fueron llevados a cabo en el período de 1980 a 2004 en el Instituto de Investigaciones y Desarrollo Agrícolas en Fundulea (Rumunía) en el chernoziom empobrecido, filtrante, formado en loess, con el contenido de arcilla de 33% y 2.8% de materia orgánica en el estrato cultivable. En el trabajo se considera la influencia de diferentes métodos de labranza de tierra (arado de vertedera, escoplo, subsolador, disqueo), fertilización y los pasos consecutivos con el tractor (1 a 3 veces antes de la preparación de presembrado en el rendimiento de girasol, cultivado en la labranza seca). Las nuevas, modernas tecnologías de producción de plantaciones deben ser adelantadas, como respuesta a reflexión sobre la influencia de la agricultura en el entorno, en la dirección de disminución de intensidad de la producción. En ese contexto, la elección del favorable método de labranza de tierra, es una decisión importante, con la cual pueden mejorarse el rendimiento y la calidad del grano. La aplicación continua de las dosis de fertilizantes óptimas (minerales y orgánicos) nos ayudó a desarrollar los sistemas de cultivo de girasol más eficaces. Las ruedas de las máquinas agricultoras causan la compresión del suelo hasta una profundidad de 40 cm, incrementada por el aumento de volumen y disminución de la porosidad total y la porosidad aérea debajo del mínimo aceptable para el desarrollo normal de las plantas. La altura de la planta y la superficie de hoja, son disminuidas por la compresión del suelo, como resultado de las empeoradas condiciones del suelo para el desarrollo de la raíz. La biomasa de la raíz ha sido disminuida por 16-33% en el suelo comprimido, en comparación con el no comprimido. RÉSUMÉ Des expériences sur un chernozem appauvri, bien drainé, formé sur le loess avec un contenu d’argile de 33 % et 2,8 % de matière organique sur une couche arable ont été effectuées dans les champs de 1980 à 2004 à l’Institut de recherche et de développement agricole de Fundulea (Roumanie). Cet article présente l’effet de différentes méthodes de labourage (charrue à soc, chisel, paraplow, disking), fertilisants et passages successifs du tracteur rangée par rangée (de 1 à 3) avant la préparation du sol sur le rendement du tournesol cultivé dans des conditions de terre sèche. Il faut améliorer les nouvelles technologies de production pour répondre aux inquiétudes concernant les effets de l’agriculture sur l’environnement en réduisant l’intensification de la culture. Dans ce contexte, le choix d’une bonne méthode de labourage est important et il peut améliorer la production et la qualité des récoltes. Une application constante des doses optimales de fertilisants (minéraux et organiques) contribue au développement d’un système de culture du tournesol plus efficace. La pression exercée par les roues cause une compression du sol jusqu’à 40 cm de profondeur, ce qui est renforci par une augmentation de la densité de la masse et une diminution de la porosité totale et de la porosité de l’air jusque sous le minimum acceptable pour le développement des plantes. La hauteur de la plante et la surface de la feuille ont diminué à cause de la compression qui forme un sol moins propice au développement des racines. Dans le sol comprimé la biomasse des racines était inférieure de 16-33% à celle des racines dans un sol non comprimé.