Stubble Tillage Research Articles

How much do conservation cropping practices mitigate runoff and soil erosion under Western European conditions: A focus on conservation tillage, tied ridging and winter cover crops

AbstractConservation farming practices are known for their capacity to mitigate runoff and erosion, but the magnitude of their effectiveness is highly variable across studies. In order to better understand the contribution of environmental and management factors to their effectiveness, up to 37 studies reporting 271 individual trials were collated for a quantitative review regarding 3 common conservation agriculture‐related practices, at the plot scale and in a Western European context. Two different methods suitable for hierarchically structured data sets were used for the meta‐analyses—hierarchical nonparametric bootstrapping and linear random effects models—, yielding nearly identical average outcomes but differing in terms of confidence intervals. We found that, on average, winter cover crops reduce cumulative seasonal (autumn‐winter) runoff by 68% and soil losses by 72% compared with a bare soil. The occurrence and intensity of stubble tillage on the control plot is a key explanatory variable for the mitigation effect of winter cover crops. In potato crops, tied ridging reduces cumulative seasonal (spring–summer) runoff by a mean of 70% and soil erosion by 92%. Conservation (non‐inversion) tillage techniques alleviate cumulative seasonal overland flow by 27% and associated sediments losses by 66%, but strong evidence of publication bias was detected for this farming practice, probably leading to an overestimation of its effectiveness. These mitigation effects are shown to be much greater for spring crops than for winter crops, and to increase with time since ploughing was stopped. The type of conservation tillage scheme strongly affects the ability to attenuate surface flows. Intensive non‐inversion tillage systems relying on repeated use of (powered) tillage operations appear to be the least effective for reducing both water and sediment losses. The best performing scheme against runoff would be a deep (non‐inversion) tillage (−61%), while against erosion it would be a no‐till system (−82%). Although several explanatory factors were identified, there remains a high (unexplained) variability between trials effect sizes, thus not attributable to pure sampling variability. Meanwhile, this review provides farm advisors or policy makers with guidance on the contexts in which implementation of such conservation practices should be supported so as to maximize expected benefits.

A new approach for modelling weed suppression of cover crops

AbstractCover cropping plays an important role in Integrated Weed Management (IWM). Weed suppression of cover crops occurs by competition, physical barrier on the soil and allelopathy. Under favourable growing conditions, cover crops can provide similar weed suppression in the autumn‐to‐spring period as repeated stubble tillage and non‐selective herbicides. The objective of this study was to test if cover crop species with higher allelopathic potential can suppress weeds in the field with less shoot biomass than cover crop species with lower allelopathic effects. Data of cover crop shoot biomass, percentage of weed suppression in the field and reduction of weed seed germination in petri‐dish bioassays treated with cover crop extracts were analysed from 11 experiments. Weed suppression in relation to cover crop biomass was better predicted by a Weibul three‐parameter model than with the Cousens model. Raphanus sativus var. oleiferus, Sinapis alba, Fagopyrum esculentum and Phacelia tanacetifolia needed at least three‐fold more biomass than Avena strigosa for 80% weed suppression. Vicia sativa had the lowest weed reduction of only 62%. Aqueous extracts of A. strigosa had the highest inhibiting effect on weed seed germination followed by R. sativus. The lowest effect was observed for P. tanacetifolia. It is assumed that for A. strigosa allelopathy strongly contributes to weed suppression whereas for P. tanacetifolia and other cover crops, competition plays the major role for weed suppression. The model can help growers and consultants to mix cover crop species for the autumn‐to‐spring period. Under dry conditions, species such as A. strigosa can provide high weed suppression with low biomass. Under moist conditions, rapidly growing cover crops such as S. alba suppress most weeds and deliver high biomass.

Productivity of the soft winter wheat cultivar ‘Duma Odeska’ depending on the characteristics of stubble tillage

Purpose. To determine the effect of surface soil tillage, carried out with the help of various agricultural machines, on its weediness, the intensity of decomposition of plant residues of winter barley and the yield of the next crop (winter wheat variety ‘Duma Odeska’). Methods. General scientific, special, field, mathematical-statistical and computationalcomparative methods were used in the research. Results. In the conditions of oversaturation of crop rotations and application of resource-saving cultivation technologies, the use of new tools for surface tillage with its simultaneous crushing, cutting of the root system of weeds and crop residues, their partial wrapping and mulching of the field surface is relevant. In 2021–2022, the greatest decomposition of winter barley stubble was observed 21 days after surface tillage with the DUCAT RST-6 rotary harrow – on average 5.1–6.5% higher values than when using the DUCAT UVT-6 vertical tillage harrow and the DUCAT-2.5 short disc harrow. The DUCAT RST-6 caused the highest weed and carrion seed germination (30–37 pcs/m2 ), the DUCAT-2.5 the lowest (13–18 pcs/m2 ). The highest grain yield of winter wheat of the variety ‘Duma Odeska’ (5.63 t/ha) in the years 2022–2023 was achieved by surface stubble cultivation with the DUCAT-2.5 implement. Conclusions. According to the results of the conducted researches it was established that the stubble tillage with the rotary harvester DUCAT RST-6 immediately after the harvest of the preceding crop (winter barle) is the most favourable for the germination of carrion and weed seeds.

Facilitation of weed seed predation by living mulch and cover crops

Weed seed predation (WSP) is an important agro-ecosystem service that naturally suppresses weed populations. Disturbances directly interfere with the activity of the seed predators, for example, harvest and soil tillage during a peak in weed seed availability (around cereal harvest). Plant soil cover and reduced soil tillage are factors that might positively affect WSP. We investigated cover crops and living mulch along with soil disturbance (no-till and conventional seeding) in comparison to a fallow and repeated stubble tillage with a chisel plough in terms of WSP, activity-density of carabid beetles and soil cover. A field experiment with a randomised complete block design and four replications was conducted at two sites from 2017 until 2019. WSP rates were assessed with seed cards and exclosure cages from July until November during a period of eight consecutive days each month. Living mulch exhibited the highest WSP rates of 72% with a maximum of 95% immediately following cereal harvest in August and September of 2017 and 2019, while the remainder of the treatments ranged from 2% to 5% WSP. In October and November mustard showed on average twice as high WSP rates compared to the other treatments (50% vs. 10%–25%). Seeding and soil tillage did not significantly influence carabid beetle activity-density and WSP, except for living mulch. Predator groups (invertebrates and vertebrates) were not influenced by the various treatments, rather year and month determined the predator groups dominance. Besides their weed suppressive effects, living mulches and cover crops also facilitate WSP.

Effect of tillage implement (spring tine cultivator, disc harrow), soil texture, forward speed and tillage depth on fuel consumption and tillage quality

Over the years, tillage became less intense due to environmental safety requirements in order to minimize fuel and labour time. Mostly, this is achieved by reducing the depth of tillage. However, highly cut winter rape stubble is the main challenge for reduced tillage to prepare clear soil, especially as the summer droughts intensify. The aim of this study was to determine the optimal tillage performances of the spring tine cultivator and compact disc harrow and establish the fuel consumption required to achieve the preferred level of soil structure formation and residue incorporation on loam and clay loam soil after a rape harvest. The fuel consumption depends on the desired level of soil tillage intensity, implement type, tillage depth (5 and 8 cm), and forward speed (1.4, 1.9, 2.5, 3.1, and 3.6 m∙s-1). The tractor “CASE IH 135” was instrumented with an additional data acquisition system and was used to perform the indicators of stubble tillage. The research examines the dependence of the tractor-implement regime mode on the soil aggregate ratio, which varied from 0.10 to 0.21, and the residue interblending ratio, which varied from 0.60 to 0.96. The relationship was established by obtaining the tillage quality level and reduced fuel consumption, which varied from 3.4 to 5.9 L·ha-1, depending on soil type. Minimization of fuel consumption and sufficient quality of oilseed rape stubble cultivation was achieved by reducing the depth but not the speed of tillage.

Exploring the Effects of Different Stubble Tillage Practices and Glyphosate Application Combined with the New Soil Residual Herbicide Cinmethylin against Alopecurus myosuroides Huds. in Winter Wheat

Effective control of Alopecurus myosuroides Huds. (blackgrass) solely with a chemical treatment is not guaranteed anymore because populations exhibit resistance to almost all herbicide modes of action. Integrated weed management (IWM) against blackgrass is necessary to maintain high weed control efficacies in winter cereals. Four field experiments were conducted in Southwest Germany from 2018 to 2020 to control A. myosuroides with a combination of cultural and chemical methods. Stubble treatments, including flat, deep and inversion soil tillage; false seedbed preparation and glyphosate use, were combined with the application of the new pre-emergence herbicide cinmethylin in two rates in winter wheat. Average densities of A. myosuroides in the untreated control plots were up to 505 plants m−2. The combination of different stubble management strategies and the pre-emergence herbicide cinmethylin controlled 86–97% of A. myosuroides plants at the low rate and 95–100% at the high rate until 120 days after sowing. The different stubble tillage practices varied in their efficacy between trials and years. Most effective and consistent were pre-sowing glyphosate application on the stubble and stale seedbed preparation with a disc harrow. Stubble treatments increased winter wheat density in the first year but had no effect on crop density in the second year. Pre-emergence application of cinmethylin did not reduce winter wheat densities. Multiple tactics of weed control, including stubble treatments and pre-emergence application of cinmethylin, provided higher and more consistent control of A. myosuroides. Integration of cultural weed management could prevent the herbicide resistance development.

Neoteinic and dwarf weeds: distribution, biology, control

Goal. To determine the features of the distribution, occurrence, biology, harmfulness and methods of control of neoteinic and dwarf weeds in the conditions of the Left Bank Steppе.
 Methods. The studies were carried out during 2017—2020 by route and expeditionary surveys. Weeds were counted 6—12 times.
 Results. Neoteinic forms and dwarf plants were found in agricultural crops throughout the growing season. The number of weeds prone to neotenia made up 43 species. The duration of the period from germination to seed ripening varied in them within 14—34 days. Plant height was 2.8—12.4 cm. Their average seed productivity did not exceed 19—21 pcs. from the plant. The mass of 1000 seeds was 12—19% higher, and the germination rate was 21—34% higher than in conventional forms. At an average density of plants, up to 3.43—3.84 thousand pieces/m2 of seeds entered the soil. Stubble ploughing and subsequent basic tillage provided 100% control of them. Late autumn application of herbicides to control neoteinic and other annual weeds was impractical. Dwarf plant species in agrophytocenoses were represented by 27 species. The number of their seedlings in winter crops ranged from 11—16 to 237—334 pieces/ m2, for spring and row crops — from 37—53 to 365—489 pieces/m2. The height of the plants was 10.8—17.5 cm, and the seed productivity was from 6 to 609 pcs. With the density of these weeds at the level of 145—160 pcs/m2, they were consumed in crops of winter wheat 18.9 kg/hectare of nitrogen, 31.0 kg/hectare of phosphorus and 27.8 kg/hectare of potassium. Average water consumption was 141 m3/hectare. The loss of wheat grain was 0.48 t/h. In the fields for grain, cereals and row spring crops, high efficiency of control in all forms and types of weeds was achieved in a system of combination of soil cultivation, which included harrowing, seed bed preparation of autumn plows, as well as the use of herbicides. In the crops of winter wheat and barley, the maximum destruction of weeds was achieved from the use of leaf herbicides in autumn 10—12 days before the end of the growing season or at the beginning of the spring growing season.
 Conclusions. The main attention in the control system of neotenic and dwarf weeds belongs to the summer-autumn technological method by 1—2-fold stubble plowing. Additionally, in sowing of spring crops, they are destroyed in the system of pre-sowing soil cultivation in combination with herbicides, and in winter crops by the use of leaf herbicides in autumn or early spring.

Non-point source pollution and long-term effects of best management measures simulated in the Qifeng River Basin in the karst area of Southwest China

Abstract Non-point source (NPS) pollution has caused serious threats to water quality on a global scale. However, the investigation using a single measure with multi-scenarios for the long-term simulation in karst agricultural watershed is still lacking. In this study, the Annualized Agricultural Non-Point Source Pollution (AnnAGNPS) model was developed to verify the applicability in a karst agricultural watershed. Then, the model was used to determine the best management measures (BMPs) and the reduction rate characteristics under long-term effects (about 10 years) in the watershed. The AnnAGNPS model perform well in simulating in NPS pollution with R2 (0.95 for runoff, 0.93 for TN, and 0.93 for TP, respectively) and NSE (0.95 for runoff, 0.53 for TN, and 0.57 for TP, respectively). The output of total nitrogen (TN) and total phosphorus (TP) primarily occurred in the rainy season (up to 80%). The loss of mass of TN and TP were mainly observed in orchards and woodlands in the upstream of each sub-basin. The results from AnnAGNPS model demonstrated that different BMPs had significant impacts on the reduction of NPS pollution. Furthermore, a same BMPs measure showed it was closely related to land use in the watershed. In the Qifeng River watershed, stubble tillage (ST) showed to be useful with relatively good reduction rates (16.64% for sediment, 17.85% for TN, and 17.80% for TP, respectively). The simulation results indicated that AnnAGNPS was a valuable tool after validation for the planning and management of the watershed in karst areas.

Efficiency of the Erosion Protection Methods Involving Biologizing Agriculture in the Steppe and Forest-steppe Areas of Cultivated Land in Siberia

The research has been carried in the steppe zone of the Minusinsk Hollow and forest-steppe of the Altai Ob Region. The paper presents the results of studying the efficiency of erosion protection methods using biologizing agriculture and technologies of soil treatment. The authors have analyzed long-term data provided by numerous research institutions located in different agro-ecological conditions in the forest-steppe and steppe areas of cultivated land. Long-term field experiments carried out to study and make a comparative analysis of soil treatment technologies in green manure fallows have shown different soil conservation efficiencies in various soil climatic conditions of the Middle Siberia. In the steppe area of cultivated land, in the case of erosion-hazard soil, it is worth using stubble mulch tillage treatment, which allows preserving plant residues on the soil surface in order to increase the soil protection efficiency of green manure fallows. After this type of treatment no removal of fine soil by wind was observed on black soil, while in the case of tillage the soil removal amounts to 2,5 - 8,1 tons per hectare per year. In the steppe area on slope lands, winter stubble residues allow one to completely prevent the soil wash out in spring. The number of days with dust storms after the Virgin Lands Campaign in Khakassia in 1961 – 1965 amounted to 5 – 13. At present, with the decreased areas of strongly eroded plough land and increased volume of fallow land, dust storms do not occur. A fallow grown crop (summer planted oats) and, on the slope lands, mulching with rape completely prevented the spring wash out. The grain yield from a hectare of the crop rotation area in the case of sweet clover tillage and stubble mulch plowing was almost the same: 1,64 and 1,76 tons per hectare, respectively. Treatment of the deposit land followed by spraying with Tornado herbicide in August reduces soil erosion 2.2 times compared to its introduction in June.

Efficiency of disc harrow adjustment for stubble tillage quality and fuel consumption

The compact disc harrow due to post-harvest tillage is used to incorporate the stubble and plant residues into soil, to induce their decomposition and to increase mineralization. The high-cut winter rape stubble is often main challenge of clear disc harrowing, especially in clay loam soil at minimum expenditure of fuel consumption. The aim of this study was to find optimal tillage performances and determine the fuel consumption what required to achieve the preferred level of stubble tillage in loam and clay loam soil after winter oilseed rape harvest. The tillage quality and fuel consumption were investigated in dependence on harrow disc angle (10°, 15° and 20°), tillage depth (5 and 8 cm) and working speed (1.4; 1.9; 2.5; 3.1; 3.6 m∙s−1). The tractor “CASE 135″ was instrumented with data acquisition system and was used to measure fuel consumption, actual working speed and implement draft. Research developed the efficient adjustment of aggregate regime mode to the best soil structure and plant residue incorporation. The beneficial relationship was established by obtaining tillage quality level to fuel consumption, which varied from 2.6 to 5.9 L·ha−1 in depending of soil type (loam and clay loam). Based on research results, the optimal fuel consumption (2.85 L·ha−1) was identified at disk harrow adjustment: disc angle 10°, working speed 3.5 m∙s-1 on both soils, but in different tillage depth 8 cm on loam and 5 cm on clay loam soil.

Weed Suppressive Ability of Cover Crop Mixtures Compared to Repeated Stubble Tillage and Glyphosate Treatments

The utilization of an effective stubble management practice can reduce weed infestation before and in the following main crop. Different strategies can be used, incorporating mechanical, biological, and chemical measures. This study aims at estimating the effects of cover crop (CC) mixtures, various stubble tillage methods, and glyphosate treatments on black-grass, volunteer wheat and total weed infestation. Two experimental trials were conducted in Southwestern Germany including seven weed management treatments: flat soil tillage, deep soil tillage, ploughing, single glyphosate application, dual glyphosate application, and a CC mixture sown in a mulch-till and no-till system. An untreated control treatment without any processing was also included. Weed species were identified and counted once per month from October until December. The CC mixtures achieved a black-grass control efficacy of up to 100%, whereas stubble tillage and the single glyphosate treatment did not reduce the black-grass population, on the contrary it induced an increase of black-grass plants. The dual glyphosate application showed, similar to the CC treatments, best results for total weed and volunteer wheat reduction. The results demonstrated, that well developed CCs have a great ability for weed control and highlight that soil conservation systems do not have to rely on chemical weed control practices.

Timing and depth of post-harvest soil disturbance can reduce seedbank and volunteers of oilseed rape

Appropriate timing of post-harvest tillage to oilseed rape (OSR, Brassica napus L.) is crucial for the creation of a soil seed bank and unwanted OSR volunteers. Existing recommendations, however, can contrast with needs for early post-harvest tillage e.g. for pest control. To specify and to systematically further improve preventive volunteer management through post-harvest tillage of imidazolinone-tolerant oilseed rape (Clearfield®; CL OSR), field experiments were set up at two locations in two separate trial periods at each location (2013–2014 and 2014–2015) in south-west Germany. After OSR harvest, and average harvest losses of 1500 m−2 seeds, or artificially broadcasting of 20000 OSR seeds m−2, stubble tillage was performed at weekly intervals (immediate (0), 1, 2, 3, and 4 weeks) at each of three depths (1–2, 6–8, and 15–17cm). To depict a worst case scenario in which herbicides were ineffective, no herbicides were applied. There were significantly smaller soil seed banks found in spring the longer the period lasted between seed rain and stubble tillage; 265 vs 145 seeds m−2 referred to 0 week vs. 4 weeks on average. Depth of stubble tillage had no significant effects on the seed number in the soil. In the first spring after seed loss, 0–2.6 CL OSR volunteers m−2 were found in the winter wheat, and the number decreased with delayed timing depth of stubble tillage. These volunteers mainly emerged in the treatment of shallow stubble tillage (1–2cm), with 0.7-0.9 flowering volunteer m−2, while volunteers averaged less than 0.04 plants m−2 in the treatment “15–17cm”. OSR volunteers in winter wheat got ripened only in one out of the four fields, and produced 1.0 seed m−2 on average. The delay between harvest and stubble tillage can be limited to approximately three weeks if stubble tillage is performed at a depth of about 6–8cm; further delay did not bring additional advantage. We recommend to retain the stubble for three weeks as further delay does not bring additional advantage, and then to apply stubble tillage deeper than 6cm. Very superficial or shallow stubble tillage should be avoided. This procedure seems appropriate for avoiding oilseed rape volunteers without use of herbicides.

Noise in cab of a crawler agricultural tractor

The working conditions of operator are considered as one of the most important indicators of technical level of a machine and its competitiveness in agricultural machinery market. The article presents the measuring data of noise level on operator workplace, based on the results of long-term tests of crawler agricultural tractors of 3 drawbar category for general purposes. Measurements of noise level in tractor cabs were carried out according to the requirements of state standards when performing the main type of works, namely the stubble tillage after harvesting of spiked cereals. Tractors produced by Volgograd tractor plant in 1993-2000 conformed to the sanitary regulations of tractors’ and agricultural machines' technology and had the noise level about 78-80 dBA. Subsequent upgrading of crawler tractor’s cab led to worsening of work conditions in respect of noise. Noise level in cab of the Agromash-90TG 1040А tractor produced by Volgograd tractor plant in 2012-2015 reached 88-90 dBA. The analysis of the results of measurement of noise levels allows to make a conclusion that the main noise source in upgraded cab is the exhaust tube of engine. The construction of cab does not protect the operator against the noise of engine. Furthermore, the use of microclimate normalization system in cab of the Agromash-90TG tractor does not provide the reduction in air temperature to a comfortable level of 24-27 degrees C. Test results revealed that working conditions on the new tractor do not conform to the requirements of standards. Specialists of tractor industry organizing a new production of crawler agricultural tractors should take into account the previous experience of engineering developments in Volgograd tractor plant and results of state tests of tractors.

Field history of imidazolinone-tolerant oilseed rape (Brassica napus) volunteers in following crops under six long-term tillage systems

Volunteer oilseed rape (OSR, Brassica napus L.) exhibits weedy behavior in crops, and can contribute to gene flow or unwanted seed admixture, particularly if its variety is tolerant to specific herbicides and if the proportion of OSR in a crop rotation is high. The aim of this study was to monitor the fate of seeds of imidazolinone-tolerant oilseed rape (Clearfield®; CL OSR) lost at harvest over the two years following its intentional sowing. A 5-yr experiment (2011–2015) with non-CL OSR and CL OSR in the same rotation was conducted on an existing long-term tillage experiment in south-west Germany to investigate OSR volunteer dynamics. The experiment included different modes of primary tillage (inversion tillage, non-inversion tillage, no-till, with or without additional stubble tillage prior to primary tillage). The crop sequence was non-CL OSR, winter wheat (Triticum aestivum L.), CL OSR (a medium and a high dormancy variety), winter wheat, and maize (Zea mays L.). High dormancy CL OSR resulted in a larger soil seed bank (147 vs. 58 seeds m−2), but in fewer volunteers (0.9 vs. 1.9 volunteers m−2) than the medium dormancy variety in the first year after CL OSR. Dormancy release likely resulted in different volunteer emergence rates of the two varieties. Immediate stubble tillage after CL OSR increased seed bank and volunteers by 0.93 and 12.7 times, respectively. Inversion tillage resulted in 30 times fewer volunteers in the first year after CL OSR, but in an equal volunteer number in the second year compared to non-inversion tillage. Slight segregation of imidazolinone-tolerant genes occurred in the offspring of CL OSR, likely leading to different CL herbicide-tolerance levels in volunteers though the number of these individuals was small.Sound strategies to control OSR volunteers should include (1) use of low dormancy varieties with low potential to establish a seed bank, (2) varieties with fast dormancy release to trigger more dormant seeds to germinate in a very short period, and (3) a period of time between harvest of OSR and first tillage operation to reduce the possibility of seeds entering soil seed bank.

Aplicação em subdose do haloxyfop-methyl na aveia-preta

Uma das limitações para sustentabilidade do sistema de cultivo em plantio direto é a rápida decomposição da matéria seca. Um dos mecanismos conhecidos para minimizar este processo e potencializar a permanência da palhada no solo é alterar as vias metabólicas dos polímeros de lignina com aplicação de subdoses de herbicida, interferindo diretamente na resistência à degradação dos restos vegetais pelos microrganismos. Com este objetivo, o herbicida Verdict*R (haloxyfop-methyl) foi aplicado em subdoses nas plantas de aveia-preta e o efeito correlacionado com a altura das plantas, produtividade da matéria seca e metabolismo de lignina. Ensaios preliminares em casa de vegetação foram realizados para determinar as faixas de subdoses a serem aplicadas no experimento definitivo em campo. Os resultados obtidos demonstraram aumento de 24% na produtividade de matéria seca dos experimentos conduzidos em casa de vegetação com a aplicação de 3,125g do ingrediente ativo de haloxyfop-methyl por hectare (i.a. ha-1) nesta subdose, não foram observadas alterações na altura e no metabolismo de lignina nas plantas de aveia-preta. No campo, a concentração de 2,5g i. a. ha-1 do haloxyfop-methyl já foi suficiente para reduzir em 9% a taxa de lignificação sem interferir na altura e produtividade das plantas, sendo este resultado favorável à velocidade de degradação da palhada no plantio direto

Vliv rozdílného hospodaření se slámou a zpracování půdy na výskyt plevelů

The weed infestation was assessed in a field experiment at the Research Institute for Folder Crops Ltd., Troubsko near Brno in 2001−2004. Numbers of individual weed species were determined using a counting method on the area of 0.25 m2 in winter wheat stands within the 6-crop rotation (peas, winter wheat, spring barley, oilseed rape, winter wheat, winter wheat) in different variants of soil tillage and straw management. The highest weed infestation in all variants was found when winter wheat followed winter wheat. The highest number of weeds was assessed in the variant with stubble tillage to the depth of 0.12−0.15 m, planting with a precision drill and straw chopping. The lowest number of weeds was found in winter wheat after peas in the variant with incorporation of chopped straw using a tiller to 0.12−0.15 m and planting with a drilling combination, and in the variant where chopped straw was sprayed with the BETA-LIQ preparation, incorporation with a tiller to 0.12−0.15 m and planting with a drilling combination.

Effects of Reduced Tillage on Crop Yield, Plant Available Nutrients and Soil Organic Matter in a 12-Year Long-Term Trial under Organic Management

A field experiment was performed in Southwest Germany to examine the effects of long-term reduced tillage (2000–2012). Tillage treatments were deep moldboard plow: DP, 25 cm; double-layer plow; DLP, 15 + 10 cm, shallow moldboard plow: SP, 15 cm and chisel plow: CP, 15 cm, each of them with or without preceding stubble tillage. The mean yields of a typical eight-year crop rotation were 22% lower with CP compared to DP, and 3% lower with SP and DLP. Stubble tillage increased yields by 11% across all treatments. Soil nutrients were high with all tillage strategies and amounted for 34–57 mg kg−1 P and 48–113 mg kg−1 K (0–60 cm soil depth). Humus budgets showed a high carbon input via crops but this was not reflected in the actual Corg content of the soil. Corg decreased as soil depth increased from 13.7 g kg−1 (0–20 cm) to 4.3 g kg−1 (40–60 cm) across all treatments. After 12 years of experiment, SP and CP resulted in significantly higher Corg content in 0–20 cm soil depth, compared to DP and DLP. Stubble tillage had no significant effect on Corg. Stubble tillage combined with reduced primary tillage can sustain yield levels without compromising beneficial effects from reduced tillage on Corg and available nutrient content.

Soil protecting effect of the surface cover in extreme summer periods

It was to investigate the effects of mulch cover and stubble tillage on soil water content and to assess grounds of recommendations in stubble management in an extreme dry period. Tests were carried out in undisturbed (U) soil, after shallow (S) and deep (D) tillage, soil with (UCO, SCO, DCO) and without surface cover (UCL, SCL, DCL) and after conventional stubble treatment (STR). Effective moisture conservation (8–11%) was observed in undisturbed soil under 55% and 65% cover ratios. The water content in the top 0.65 m soil layer increased significantly (LSD, P < 0.05) between the different stubble variants, the following order was established on day 85: DCL < STR < SCL < UCL < DCO < SCO < UCO. The conventional stubble management cannot be applied in soils after shallow (STR) or deep tillage (DCL) in a dry season, when the loss of water is even statistically proven. Leaving the soil without a cover (UCL) or having it with insufficient cover (< 15%) entails risks in soils. Increasing the soil cover ratio (from 5% to 75%) had a 1.3–2.3 times stronger impact on crumb forming than did the moisture recorded in the various seasons.

Long-term yield and weed response to conservation and stubble tillage in SW Germany

The study provides information to more reliably estimate the value of conservation tillage in a temperate climate. Tillage effects on yield and weeds were evaluated in field experiments at two sites in SW Germany between 1999 and 2010. Tillage varied at site Ihinger Hof from mouldboard plough (P), chisel plough (CP), rototiller (RTT), varying P and CP (VAR), to no tillage (NT), partially combined with stubble tillage (S). Tillage at site Meiereihof was S/P, S/CP, and NT. Crop rotations included winter wheat (WW, Triticum aestivum), triticale (TR, Triticosecale), oat (OA, Avena sativa), silage maize (SM, Zea mays) and oilseed rape (OSR, Brassica napus) at Ihinger Hof, and winter wheat, spring barley (SB, Hordeum vulgare), silage maize, sugar beets (SBE, Beta vulgaris) and faba bean (FB, Vicia faba) at Meiereihof. At Ihinger Hof, tillage had an effect on yield (P>F=0.0049), but no effects were found on crop emergence and crop density. Tillage effects on yield were consistent across crops though differences between crops appeared to exist. The yield of S/P, the standard tillage, was 8.5 (WW), 7.7 (TR), 4.7 (OA), 18.3 (SM) and 4.1 (OSR)tDMha−1 at Ihinger Hof, with yield under NT always significantly lower than S/P by 7.3% on average for all crops. At Meiereihof, yields ranged from 7.2 to 8.0 (WW), 3.3 to 4.2 (SB), 19.8 to 21.5 (SM) and 3.1 to 3.2 (FB)tDMha−1, and 61.3 to 67.6 FM ha−1 for SBE. Yield was reduced by 4.5% from S/P to S/CP (P>F=0.0516), and by about 10% from S/P to NT (P>F=0.0009).Weed density ranged between 0.5 and 44plantsm−2 at Ihinger Hof and was higher in treatments without stubble tillage and under non-inversion tillage, though significance differed for the different classes of weeds. NT led to weed infestation about 2–20 times higher than S/P. The interaction crop×treatment indicated that factors other than tillage influenced weed infestation.It is unlikely that weed infestation and reduced yield will be problems in temperate climates if soil disturbance through tillage is reduced. Non-inversion tillage can easily replace inversion tillage, and stubble tillage can be added to primary tillage if needed to reduce weeds. Since no specific tillage method was unequivocally superior to another one, any method well suited to specific regional and farm conditions can be adopted successfully.

On the way towards conservation tillage-soil moisture and mineral nitrogen in a long-term field experiment in Germany

Ten years of a long-term field experiment using different strategies of conventional and conservation tillage in SW Germany were evaluated for soil mineral nitrogen (SMN) and soil moisture content. Treatments analysed were combinations of stubble tillage (S) or no stubble tillage with primary tillage P: mouldboard plough, CP: chisel plough, RTT: rototiller, NT: no-till, and VAR: alternating S/P or S/CP. Best management practices were used for crop rotation, fertilisation and plant protection. CP, VAR and NT resulted in 18.7–19.0% gravimetric water content in spring. Partially significantly lower water content was observed in spring under S/P and CP with 18.2%; P and S/RTT resulted in 18.5%. Autumn soil moisture ranged from 15.3 to 15.8% and did not significantly differ between the treatments. Interactions between treatment and depth were not significant. There was no clear trend for spring soil moisture. No treatment showed a particular response to dry or wet season. Total SMN ranged between 8 and 49 kg ha −1 in spring and 5–26 kg ha −1 in autumn; significant effects of the treatments or interactions of treatment × depth did not occur. The effect of the season was most relevant for the amount of SMN, probably as a result of different conditions for mineralisation. Downward movement of nitrogen in spring was low in all treatments if catch crops were grown in the previous autumn. Overall, different soil tillage methods had little effect on soil moisture and soil SMN under temperate conditions. Seriously adverse effects of any tillage treatment in terms of nitrate leaching or reduced mineralisation seem unlikely. Similarly, the tillage systems did not exhibit obvious advantages or disadvantages in terms of soil water content. An exception may have been the higher water content in autumn in 0–30 cm under high soil disturbance which provided more suitable conditions for germination of the following crop. The decision of whether or not to adopt conservation tillage in temperate climates seems not to be primarily dependent on soil moisture and nitrogen mineralisation or on nitrogen leaching.