Soil changes due to long term effect of certain tillage system-Tillage Practices and Soil Management | Crop Production Notes- Agricultural Engineering PDF Download

Current tillage systems within Poland can be divided into 2 broad categories: inversion tillage, known as conventional tillage, and noninversion tillage, known more widely as conservation tillage with shallow cultivation or direct drilling. Conservation tillage has numerous positive eff ects on soil, such as improvement of water content (Husnjak et al. 2002; Boydaş and Turgut 2007) and reduction of soil erosion (Holland 2004; Morris et al. 2010). However, noninversion tillage can also lead to soil compaction, which could aff ect seed germination, root growth, and crop yield (D’Haene et al. 2008). Th e most common variables used to assess soil compaction in tillage studies are bulk density and penetration resistance. In several studies comparing tillage systems, greater bulk density and penetration resistance were found under reduced tillage and direct drilling, especially in the upper layer, than under conventional tillage (Özpinar and Çay 2005; McVay et al. 2006; Blecharczyk et al. 2007; Boydaş and Turgut 2007; Th omas et al. 2007). 

Changes in soil condition due to surface residue accumulation in continuous conservation tillage are substantial and characterized by increased soil organic matter (Blecharczyk et al. 2007; Fernández et al. 2007; Martin-Rueda et al. 2007; Th omas et al. 2007; López-Fando and Pardo 2009). Th e progressive increase in organic matter content in the fi rst few centimeters of the soil profi le increases the availability of the main nutrients (Fernández et al. 2007; MartinRueda et al. 2007; López-Fando and Pardo 2009), which are released to the rhizosphere at a faster rate than in conventional tillage (Fernández et al. 2007). Moreover, slower decomposition of surface-placed residues may prevent rapid leaching of nutrients through the soil profi le, which is more likely when residues are incorporated into the soil. 

Physical and chemical processes continually interact with time, resulting in a diversely arranged mixture of soil minerals, organic matter, and pore spaces that together define soil structure (Blanco Canquietal. 2005). Derpsch (2007) indicated that positive changes in soil properties are diffi cult to detect aft er only 2 or 3 years. 

It is diffi cult to estimate the consequences of changes in soil quality on seed emergence and the growing conditions of plants. Changes in the same property can have diff erent eff ects for crop growth and yield (Małecka et al. 2004; Angas et al. 2006; Machado et al. 2007; Martin-Rueda et al. 2007; Lepiarczyk and Stępnik 2009; Jug et al. 2011), depending on dominant soil and climatic conditions. 

Th e objective of this experiment was to determine the eff ects of long-term tillage system combinations on some physical and chemical properties of soil and the crop yield of spring barley. 

Materials and methods The studies, carried out over the years 2003-2006, involved a static field experiment initiated in 1999 at the Brody Research Station of the Poznan University of Life Science, Poland (52°26ʹN, 16°17ʹE) on a soil classified as Albic Luvisols developed on loamy sands overlying loamy material (12% clay, 19% silt, and 69% sand). Th e 0-20 cm soil layer had 1.4% organic matter; a pH of 6.5 (measured in 1 M KCl); available P, K, and Mg concentrations of 207, 119 and 32 mg kg^–1, respectively; and a bulk density of 1.41 Mg m^–3 at the beginning of the experiment. Prior to the start of this experiment, only plowing tillage had been applied for crops (mainly cereals) and the straw of cereals had been removed.

A spring barley cultivar, Atol, was grown in a 4-year rotation of peas, winter wheat, spring barley, and winter triticale. The sowing rate was 400 seeds m^–2 for all tillage sown. The 3 tillage systems were arranged in a randomized block design in 4 replications, resulting in a total of 12 plots. Th e size of each tillage plot was 30 m in length and 5 m in width. Th e plots were separated by buff er strips of 0.3 m and there was a 6-m gap between the blocks for the tractor. Th e straw of the previous crop (winter wheat) was removed from all plots in all years. 

Th e following tillage systems were applied in continuation: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). The CT consisted of tilling with a disk harrow (2.5 m wide) to a depth of 8 cm aft er the harvest of the previous crop, autumn plowing to a depth of 25 cm with a 3-furrow reversible plow (in the fourth week of October), and presowing tillage for seedbed preparation with a fi eld cultivator followed by harrowing and rolling to a depth of 8 cm in the spring (1 week before sowing). Th e RT was done in the autumn (the fourth week of October) with only a stubble cultivator (2.5 m wide). Th e NT involved sowing directly into the stubble of the previous crop. Th e CT plots were drilled with a traditional grain drill (Poznaniak L, 2.5 m wide, row distance of 15 cm), and the RT and NT plots were drilled with a double disk drill (Great Plains, Solid Stand 10’ equipped with a fl uted coulter for residue cutting, a double disk for seed placement, and a single press wheel, 3.05 m wide, row distance 17.8 cm). A Zetor Forterra 10641 tractor was used for all tillage systems and sowing. Th e operating speed used for plowing and drilling was 1.5 m s^–1, and 1.8 m s^–1 was used for other tillage treatments (cultivator and disk harrow). Speed was measured using a stopwatch and engine tachometer. Sowing dates were dependent on soil water conditions and occurred between March 25 and April 5, and the sowing depth for all tillage systems was 3-4 cm. 

Fertilization was uniform for all tillage systems and each experimental year (90 kg N ha^–1, 35 kg P ha^–1, and 66 kg K ha^–1). Th e herbicide program for the tillage systems used preplant and postemergence applications. Before planting, 3 L ha^–1 of glyphosate herbicide was applied on all plots with no-tillage and reduced tillage to control perennial weeds and volunteers. For weed control during the postemergence growing season, Stork 50 WG herbicide (thifensulfuron-methyl + carfentrazoneethyl) was applied at the rate of 0.06 kg ha^–1. Th e seeds were dressed with Raxil Extra 060 FS fungicide (0.06 L 100 kg seeds^–1) containing thiuram and tebuconazole. For disease control, Folicur Plus 375 EC fungicide (tebuconazole + triadimenol) at the rate of 1.2 L ha^–1 was applied to all plots at the GS 31 growth stage (Zadoks et al. 1974).

Measurements of penetration resistance (MPa), bulk density (Mg m^–3), and volumetric water content (%) of the soil were taken at the stem elongation growth stage (GS 31) of spring barley. Penetration resistance was measured for the depths of 0-10 cm, 10-20 cm, and 20-30 cm with a total of 16 replications for each tillage treatment and year. A hand-pushed penetrometer (Eijkelkamp Agrisearch Equipment, Model 06.01 Eijkelkamp, Giesbeck, the Netherlands) was used for the measurements with a cone diameter of 11.28 mm (cone number 1) in RT and NT and with a cone diameter of 15.96 mm (cone number 2) in CT. Th e area of the cone base was 1 cm2 for cone number 1 and 2 cm² for cone number 2, and the tip angle was 30°. Soil bulk density was determined by the core method (Blake and Hartge 1986) at depths of 0-5 cm and 10-20 cm using 100 cm³ cores (in 16 replications for each depth, tillage treatment, and year). Th e same cores were used to determine volumetric water content in the soil. Soil samples for chemical analyses were collected aft er the harvest of spring barley in 2006. Th e replication plot was represented by a mean sample consisting of 10 individual samples collected using an Egner sampler from the 0-5 cm and the 10-20 cm layer. Aft er drying, the soil was crushed by hand and sieved through a 2-mm sieve. Organic carbon was determined using the Tiurin oxidation method, total N using the Kjeldahl method, available forms of P and K using the Egner-Riehm method, and available Mg using the Schachtschabel method (Page et al. 1982). Barley was harvested annually in early August from a 20 m2 area using a 1.5-m wide Wintersteiger Classic Plot Combine. Grain yield was recalculated on standardized 15% grain moisture weight for t ha^–1. Th e following quality parameters of the spring barley were assessed: plant density per square meter at the beginning of tillering (4 frames with dimensions of 0.25 m2 in growth stage GS 21), number of ears per square meter before harvest (4 frames with dimensions of 0.25 m2 in growth stage GS 75), number of grains per ear (some 50 plants), and 1000-grain weight in grams (grains collected from the harvested grain mass; 2 × 500 grains were counted and weighed). 

Th e results were tested using standard variance analysis (ANOVA) for the randomized complete block. Mean separations were made for signifi cant eff ects with LSD and Tukey tests at probabilities of P < 0.05 and P < 0.01.

Results The mean air temperatures during the vegetation period of spring barley (March-July) were higher than the 40-year mean, except in July 2004, March and May 2005, and March 2006 (Table 1). Growing season precipitation (March-July) in 2003, 2004, and 2006 was lower in comparison to the 40-year mean, except in 2005. Precipitation in 2003, 2004, and 2006 reached 70%, 75%, and 52% of the long-term mean value, but total precipitation during the season of March-June 2003 was lower than the 40-year mean. In 2005, the total precipitation was marginally higher, but precipitation shortages occurred in March, April, and June. Th us, weather conditions for the development of spring barley were the least favorable in 2006 and less favorable in 2003 than in the other years. 

Physical properties of soil It was found that tillage systems signifi cantly aff ected the physical properties of the soil (Table 2). Th ere was a signifi cant diff erence in the soil water content with RT or NT in comparison to CT at both depth measurements. Th e soils tilled under RT and NT had higher recorded water content values, especially in the top layer. Volumetric water content values in the 0-5 cm soil layer increased by 3.1% under RT and 5.4% under NT relative to CT (P < 0.01). Water .

Table 1. Mean daily air temperatures and total precipitation in the vegetation period of spring barley in 2003-2006 and 1961-2002 (from the Agrometeorological Observatory in Brody). 

Table 2. Volumetric water content and soil bulk density as aff ected by tillage system (mean of 2004-2006). 

content values in the 10-20 cm soil layer increased by only 1.6% under RT and 2.5% under NT relative to CT (P < 0.05). In the 10-20 cm soil layer, the diff erence in soil water content between RT and NT was not signifi cant.

The soil tillage systems signifi cantly modifi ed soil bulk density in the spring vegetation period of spring barley only in the upper soil layer (P < 0.01) (Table 2). At the 0-5 cm depth, RT caused an increase in the soil bulk density value in the surface soil layer of 0.15 Mg m^–3, and NT caused an increase of 0.30 Mg m^–3 as compared with CT. Diff erences in bulk density between tillage systems were not signifi cant at the 10-20 cm depth; however, bulk density in CT was slightly lower than in RT and NT. 

Penetration resistance depends on the tillage system and its depth (Figure). Penetration resistance showed an increasing trend with depth for all treatments. During the growing period, there were statistically signifi cant diff erences between the tillage

Figure. Penetration resistance as aff ected by tillage system: conventional tillage (CT), reduced tillage (RT), and notillage (NT) (means of 2004-2006). NS: not signifi cant; P < 0.05. Th e means in a row with the same letter are not signifi cantly diff erent.

systems in penetration resistance at the 0-10 cm depth (P < 0.01). Th e highest penetration resistance was obtained in NT (1.56 MPa), and the lowest in CT (1.19 MPa). On the other hand, in the 10-20 cm layer, the applied soil tillage systems did not result in signifi cantly diff erent soil penetration resistance. At the 20-30 cm depth, the opposite result was recorded because the determined parameter was signifi cantly higher in CT (2.36 MPa) than in RT (1.99 MPa) and in NT (1.89 MPa), which may be a result of the development of a plow pan in CT (P < 0.01). Diff erences in the penetration resistance of the layers at 20-30 cm were not signifi cant between RT and NT.

Chemical properties Conservation tillage systems lead to changes in nutrient distribution in the soil layer (Table 3). One of the eff ects produced by the diff erent tillage systems aft er 7 years was the accumulation of organic C and total N at the soil surface under RT and NT. Th e concentration of organic C in RT, and particularly in NT, had increased signifi cantly in the top layer (0-5 

Table 3. Organic C, total N, and available forms of P, K, and Mg concentrations in the soil at the end of 7 years under conventional tillage (CT), reduced tillage (RT), and no-tillage (NT).

cm), by 18.3% and 26.1%, respectively, in comparison with CT (P < 0.01). Stocks of organic C in the 10-20 cm depth, in contrast, were signifi cantly lower in NT plots than in the plots under CT practices. Diff erences between N stocks under tillage systems in the surface layer (0-5 cm) closely followed the pattern observed for organic C. Total N concentrations in RT and NT were greater by 10.4% and 16.7%, respectively, than under CT, but no signifi cant diff erences between tillage systems appeared at the 10-20 cm interval. Measurements showed no signifi cant diff erences in concentration of total N between RT and NT at the 0-5 cm intervals. Th e highest C-to-N ratio was obtained at the top soil layer (0-5 cm) of the NT plots, but no signifi cant diff erence was observed between NT and RT. Th e diff erence in soil C-to-N ratios between tillage systems was not signifi cant at the 10- 20 cm depth. 

Concentrations of available K and Mg were greater in the soil surface layer (0-5 cm) under RT by 36.9% and 19.7%, respectively, and under NT by 51.0% and 37.5%, respectively, than under CT (Table 3). Th e situation was reversed in a deeper layer (10- 20 cm), where available K and Mg were greater in CT. Th ere were no signifi cant eff ects of tillage practices on available P in the 0-5 cm and 10-20 cm layers.