Grain yields and soil properties on loam soil after three decades with conservation tillage in southeast Norway

Four tillage trials have been performed on moderately well-drained loam soil in southeast Norway for 30–37 years (mean 34), comparing reduced tillage (8–10 cm in spring) with autumn ploughing (25 cm). In some years, additional stubble harrowing in autumn (10–12 cm) was compared with harrowing only in spring. Weeds were controlled with herbicides. Straw residues were retained after around 1990 and no fungicides were used. Grain yields are reported for the last nine years, and compared with earlier years. Results are presented for a number of soil properties measured in recent years. Autumn harrowing gave no consistent yield benefit over harrowing only in spring. There was little difference between ploughed and unploughed treatments in mean grain yields over the whole trial period, and the variability between years was similar in both tillage systems. Relative grain yields, calculated as yields obtained without ploughing in percentage of those obtained with ploughing, appeared to be normally distributed around 100%. Responses were often positive in dry years, and negative in wet years. Reduced tillage gave higher P and K concentrations near the soil surface and slightly lower concentrations in deeper layers. There was little change in their levels, relative to earlier findings. Changes in bulk density and total porosity were mostly attributable to changes in the stratification of organic matter. Reduced tillage increased porosity at 4–8 cm depth and decreased it slightly at 24–28 cm, but there was no change in the intermediate layer. The moisture-holding capacity of the soil was altered little by reduced tillage, and soil aeration properties were satisfactory at all three depths measured. There was no change in the total amount of organic matter stored within the topsoil, despite marked changes in its distribution. Reduced tillage gave significant increases in aggregate stability and an indication of greater earthworm activity.     

Effects of ploughless tillage and straw incorporation on evaporation

The effects of ploughness tillage (stubble cultivation with a disc tiller or a spring tine cultivator, or with both in combination, replacing mouldboard ploughing) on evaporation were investigated using undisturbed soil lysimeters (height = 350 mm, diameter = 300 mm) excavated after spring cultivation in May from field experiments in eastern Sweden. The evaporation process was measured on ploughed and unploughed soil lysimeters, both with or without precipitation and with or without a seedbed. The effects on evaporation of incorporating crop residues with or without precipitation into a ploughed seedbed were also measured. The results from a heavy clay and from a silty clay loam showed that both ploughless tillage and incorporated straw reduced cumulative evaporation. The water-conserving effect was greater in irrigated treatments. The positive effect on water conservation was also greater on the silty clay loam than on the heavy clay. The soil structural changes brought about by ploughless tillage in layers under the seedbed acted to reduce the rate of evaporation from soil.     

Ploughless tillage in Sweden. Results and experiences from 15 years of field trials

Results and experience from 140 field trials carried out during the period 1974–1988 are presented. The whole of Sweden was represented in the investigation, but the majority of sites were in the central and southern areas of the country. In the unploughed experimental plots, conventional autumn ploughing to 20–25 cm was compared with two or three stubble cultivations to approximately 10–12 cm depth. on average, use of ploughless tillage reduced yields of winter wheat, spring barley, winter and spring oilseed rape and sugarbeet and somewhat improved yields of oats and potatoes. The results from ploughless tillage were generally improved by the use of dual rear tractor wheels instead of single wheels, by the placement of artificial fertilizer instead of broadcasting and by the removal of straw. The incidence of annual weeds increased on average by 25% and stoloniferous weeds by 100%. The most suitable soils were peats, sandy loamy tills, silty loams or silty clay loams and heavy clays.     

Recent yield results and trends over time with conservation tillage on morainic loam soil in southeast Norway

Abstract

Results for 1998–2004 are reported from four long-term (25–28 years) tillage trials, comparing conventional autumn ploughing with reduced tillage, normally spring harrowing only. Plant residues were retained during the period studied. The weather was somewhat wetter than the 1961–1990 normal. Results with reduced tillage were mostly similar to those seen in earlier trial periods. In Trial 1, mean grain yield was 95% with spring harrowing only versus autumn ploughing, 96% when harrowing in autumn was performed as well and 97% when the soil was ploughed every third year. In Trial 2 positive crop rotation effects were found both with and without ploughing, and reduced tillage gave 5% lower grain yield also in this trial. In Trial 3, tillage system did not affect yields of cereals grown in rotation with potatoes, but reduced tillage gave 12% lower potato yield than ploughing. Little difference in response to N fertilizer was found. In Trial 4, reduced tillage on large-scale (0.7 ha) plots gave 11% lower grain yields than annual ploughing, partly due to shallow sowing depth. No long-term trend in yield responses to tillage was discernible in any trial, and between-year variability was similar with both ploughing and reduced tillage. Percentage yields with reduced tillage relative to annual ploughing correlated positively with rainfall in May and with mean air temperature in August. It is concluded that the reduced tillage systems studied are sustainable in terms of productivity, relative to labour, machinery and energy inputs. Likely benefits of such systems include higher levels of organic matter and aggregate stability in surface soil horizons, but a disadvantage is the need for frequent herbicide use to control perennial weeds.     

Soil mineral-N and N-fertilizer requirements of spring cereals in two long-term tillage trials on loam soil in southeast Norway

Much uncertainty exists among growers concerning the need to adjust N-fertilizer application to cereals when reduced tillage is adopted. Studies in long-term trials are required to give an adequate answer to this question, which is of both economic and environmental interest. N-fertilizer requirements of spring cereals and of soil mineral nitrogen contents at different times of the year were measured over the period 1991–1996 in two long-term tillage trials established in 1980 at Kise (60°46′N, 10°49′E) on morainic loam soil. Tillage treatments comprised conventional tillage with autumn ploughing and reduced tillage without ploughing and with harrowing in spring kept to the minimum necessary for seeding. Four levels of N-fertilizer (0, 60, 90 and 120 kg N/ha) were compared in 1991–1995 in barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.), and their residual effect was measured in 1996. Levels of soil mineral nitrogen before fertilization in spring were on an average 8% lower with reduced tillage than with conventional tillage. Plant development was delayed with reduced tillage, but this was compensated for later in the season. A two-year incubation study under covered plots in the field did not reveal any effect of tillage on net nitrogen mineralisation. There was a tendency to higher straw yield with reduced tillage, but no overall effect on grain yield. Responses to N-fertilizer were almost identical with both the tillage systems, and yields increased up to the highest level of application. Crop nitrogen contents were monitored, but only minor differences were found between tillage systems in total uptakes and apparent N-fertilizer recoveries. On the basis of these results it is concluded that long-term reduced tillage does not affect the N-fertilizer requirements of spring cereals on loam soils under cool climatic conditions.     

Residue cover,soil structure,weed infestation and spring cereal yields as affected by tillage and straw management on three soils in Norway

Four field trials (spring wheat and oats) were conducted (one on clay soil, one on loam soil and two on silt soil) for three years in important cereal growing districts, to investigate the influence of tillage regimes (ploughing versus reduced tillage in either autumn or spring) and straw management (removed and retained) on plant residue amounts, weed populations, soil structural parameters and cereal yields. The effect of tillage on soil structure varied, mainly due to the short trial period. In general, the amount of small soil aggregates increased with tillage intensity. Reduced soil tillage, and in some cases spring ploughing, gave significantly higher aggregate stability than autumn ploughing, thus providing protection against erosion. However, decreasing tillage intensity increased the amounts of weeds, particularly of Poa annua on silt soil. Straw treatment only slightly affected yields, while effects of tillage varied between both year and location. Reduced tillage, compared to ploughing, gave only small yield differences on loam soil, while it was superior on clay soil and inferior on silt soil. Our results suggest that shallow spring ploughing is a good alternative to autumn ploughing, since it gave comparable yields, better protection against erosion and was nearly as effective against weeds.     

Verification of traffic-induced soil compaction after long-term ploughing and 10 years minimum tillage on clay loam soil in South-East Norway

Grain yields are presented from a 10-year field trial with four tillage regimes (annual ploughing, harrowing only, ploughing/harrowing alternate years and minimum tillage) on clay loam. We also present soil physical analyses and use the compaction verification tool (CVT) to assess compaction on plots with annual ploughing and minimum tillage, after using slurry tankers with contrasting wheel loads (4.1 Mg, 6.6 Mg) and wheeling intensities (1×/10×) in the 11th trial year, and yields monitored two years after compaction. Winter wheat yields in the period before compaction were strongly affected by tillage, with annual ploughing giving on average 24% higher yield than direct drilling. Both wheat and oats were far less affected in treatments with harrowing only or ploughing/harrowing alternate years, on average within 6% of annual ploughing. Yields after compaction were affected by both previous tillage and compaction intensity. In the first year, single wheeling after annual ploughing gave 23% yield reduction with 4.1 Mg wheel load and 28% reduction with 6.6 Mg wheel load, whilst multiple wheeling gave 14% reduction at 6.6 Mg wheel load. Yield reductions after minimum tillage ranged from 63% (single wheeling with 4.1 Mg) to 100% (multiple wheeling with 6.6 Mg). Similar trends were found in the second year. The soil physical data indicated that all wheeling led to changes in bulk density, pore sizes and permeability in both topsoil and subsoil on both sampled tillage plots. However, effects in the subsoil were partly masked by the soil's high initial bulk density, partly due to its high clay content. The CVT, which plots air capacity against hydraulic conductivity, suggested some harmful compaction on both plots, with the minimum tillage plot being less affected than the ploughed plot. However, yield results did not support this conclusion, indicating that other factors limited yields on the minimum tilled plot.     

Movement of suspended matter and a bromide tracer to field drains in tilled and untilled soil

Abstract. Drainage water was sampled intensively during a four-year field experiment on a sandy loam soil subjected to four unreplicated tillage treatments: (1) harrowing with a springtine harrow, drilling; (2) direct drilling; (3) ploughing with light subsurface compaction, one pass with a PTO-driven rotary harrow, drilling; (4) ploughing, one pass with a springtine harrow, drilling. In all years, the losses of suspended matter with drainage water (0.1–4.3 kg ha⁻¹ yr⁻¹) were smaller by a factor of 1.9 or more from direct drilled plots than from plots subjected to the other tillage treatments, strongly suggesting that tillage increased the losses. Annual bromide losses were governed by the amount of drainage water rather than by the tillage treatments. However, after one drainage season, more bromide was left in the soil at 0–100 cm depth with ploughless tillage than with ploughing, thus indicating more bypass flow without ploughing. The study demonstrated very changeable patterns of suspended matter and bromide concentrations in drainage water sampled from large field plots, and questions the representativeness of drainage water samples for water reaching the subsoil or shallow groundwater.     

Optimizing farmyard manure utilization by varying the application time and tillage strategy

Abstract. Two field experiments were carried from 1999 to 2001 to assess the effectiveness of autumn, winter and spring application of straw-based farmyard manure (FYM). The soil was a sandy loam containing 106 g clay kg⁻¹ situated in the temperate coastal climate of Denmark. The FYM was applied manually to experimental plots at a target rate of 300 kg N ha⁻¹. The manure was incorporated by three initial tillage strategies (harrowing, rotavating or no-tillage) prior to ploughing. All combinations of tillage strategies were also carried out without manure application. Spring barley ( Hordeum vulgare L.) was grown, followed by ryegrass ( Lolium perenne L.). The results suggest that, as far as circumstances permit, FYM should be applied in spring to achieve the optimum use of nitrogen in the manure. Further, yield and nitrogen uptake did not benefit from harrowing or rotavating the manure before ploughing. When manure was not applied, soil tillage prior to ploughing did not significantly affect grain yield or nitrogen uptake.     

The influence of tillage methods on soil physical properties and water balance for a typical crop rotation in SW Spain

In the present work the effect of several tillage methods on the physical properties of a sandy clay loam (Haploxeralf) from Seville province (SW Spain) has been studied in order to establish the optimum management for water intake and conservation in the soil.

The following tillage methods were considered during the period 1984–1987: disc ploughing; mouldboard ploughing; cultivator application; disc harrowing; no-tillage. Two crops were used in rotation, wheat and sunflower. In each treatment, soil susceptibility to compaction and systematic measurements of resistance to penetration, bulk density, hydraulic conductivity and infiltration rate in the top layer were carried out. Changes in water profiles through the experimental period were also followed. The results presented in this paper correspond to the period autumn 1986–July 1987, the third year of rotation. They show important differences in soil physical properties as well as in the rate of replenishment and depletion of soil water storage as a result of treatments. Differences in crop response have also been observed.     

Nitrate leaching as influenced by soil tillage and catch crop

Because of public and political concern for the quality of surface and ground water, leaching of nitrate is of special concern in many countries. To evaluate the effects of tillage and growth of a catch crop on nitrate leaching, two field trials were conducted in spring barley (Hordeum vulgare L.) under temperate coastal climate conditions. On a coarse sand (1987–1992), ploughing in autumn or in spring in combination with perennial ryegrass (Lolium perenne L.) as a catch crop was evaluated. Furthermore, rotovating and direct drilling were included. The experiment was conducted on a 19-year-old field trial with continuous production of spring barley. On a sandy loam (1988–1992), ploughing in autumn or in spring in combination with stubble cultivation and perennial ryegrass, in addition to minimum tillage, was evaluated in a newly established field trial. For calculation of nitrate leaching, soil water isolates from depths of 0.8 or 1.0 m were taken using ceramic cups. No significant effect of tillage was found on the coarse sand; however, a significant effect of tillage was found on the sandy loam, where leaching from autumn ploughed plots without stubble cultivation was 16 kg N ha⁻¹ year⁻¹ higher than leaching from spring ploughed plots. Leaching was significantly less when stubble cultivation in autumn was omitted. Leaching on both soil types was significantly reduced by the growth of a catch crop which was ploughed under in autumn or in spring. It was concluded that soil cultivation increased leaching on the sandy loam but not on the coarse sand, and that the growth of perennial ryegrass as a catch crop reduced leaching on both soil types, particularly when ryegrass was ploughed under in spring.     

Effects of reduced tillage and liming on microbial activity and soil properties in a weakly-structured soil

The effects of reduced tillage and lime on crop yield and soil physical and microbial properties were studied in a weakly-structured silty clay loam soil. Two autumn primary tillage practices were compared, mouldboard ploughing to 20–25 cm and cultivation to 12 cm. Seedbed preparation was carried out by several harrowing operations in the mouldboard ploughed treatment, and with a PTO-driven harrow in the same operation as sowing in the shallow cultivation treatment. The tillage treatments were applied alone or were combined with liming aimed at soil structural improvement. Lime was added as 6.5 Mg CaO ha⁻¹ before the start of the experiment and mixed into the top 12 cm of soil with a disc cultivator. A 4-year crop rotation was used: spring barley, spring oilseed rape, spring/winter wheat and oats, and all crops were compared each year. Crop residues were retained in the experiment and incorporated at cultivation. Aggregate stability was improved by the shallower tillage depth, probably as an effect of an increase in soil organic matter and a more active microbial biomass. Liming had little effect on soil structure variables but increased microbial activity to some extent. This was reflected in higher crop yields, especially when the shallow tillage depth was combined with liming. Penetration resistance in the seedbed subsoil was highest when mouldboard ploughing was carried out in plots without liming. Data were examined with principal component analyses, and the structures in the data were presented as scores and loading plots, which revealed groupings between samples and relationships between variables, respectively.     

A long-term comparison of ploughing, tine cultivation and direct drilling on the growth and yield of winter cereals and oilseed rape on clayey and silty soils

The effects of mouldboard ploughing, shallow tined cultivation and direct drilling on yields of winter wheat, barley, oats and oilseed rape were compared over 10 years. Three field experiments were conducted on two non-calcareous clays (stagnogleys) and a weakly structured silty soil (argillic brown earth). Two spring N levels were applied to the winter wheat plots on the clay soil in three years and to the winter barley plots on the silty soil in one year. This paper reports the soil bulk density and water content at sowing and the crop growth, yield components and yields obtained during the later years of the study: 1979–1984 on the clayey soils and 1981–1984 on the silty soil.

In the years when cereals were grown, differences in yield between cultivation treatments were small and inconsistent. Oilseed rape yielded significantly more after direct drilling than ploughing because of better establishment and uniformity of growth.

The success of continuous reduced tillage depended on both burning crop residues and good weed control.     

Effect of mouldboard and chisel ploughing and their timing on seedbed quality

The effects of tillage on weed growth are supposed to depend largely on the type of implement, the timing of the operation and the type of soil. Experiments on the effect of mouldboard and chisel ploughing with duckfeet, used for the main tillage operation and the timing of the main tillage operation on seedbed quality and weed development in sugar-beet were carried out from 1981–1983 on silty clay, silty loam and two sands. Seedbed quality was only slightly influenced by type and timing of the main tillage operation. Soil texture affected seedbed quality significantly: seedbeds on light soils compared with silty soils had a finer tilth, were deeper and were scarcely sorted (stratified according to particle size). Chisel ploughing with duckfeet to the full depth of the arable layer required much tractor power and during the late autumn on silty loam and in spring on sand, chiselling was impossible because the soil was too wet; the mouldboard plough did not cause problems of this kind. Moreover, soil inversion by the mouldboard plough was attended by a surface free of crop residues and weeds after the main tillage operation and a strong suppression of weeds during winter, sowing time and in the young crop.     

Direct drilling and soil loosening for spring cereals on a fine sandy loam in Atlantic Canada

Changes in soil structure and properties, plant growth and diseases and agronomic aspects were determined, after 3 years, on a Charlottetown fine sandy loam, an Orthic Podzol with a perhumid soil moisture regime, subjected to three tillage systems for spring cereals. The tillage systems consisted of direct drilling, soil loosening with a “paraplow” followed by direct drilling and mouldboard ploughing.

Rate of plant growth and other crop measurements were not changed by the tillage systems, except for the depth of seeding. Direct drilling reduced the accumulation of N and K in the plant, and reduced grain N, compared with mouldboard ploughing. Soil loosening prior to direct drilling prevented the decline in N and K accumulation, and increased grain yield and N content, in comparison with mouldboard ploughing. Direct drilling caused changes in soil macro-aggregation and reduced the evaporation rate, and increased microbial biomass C and N, total organic C and N and extractable ions at the soil surface (0–5 cm), compared with mouldboard ploughing. In addition, earthworm numbers were increased under direct drilling. Root lesion and spiral nematodes were not influenced by tillage differences.

Soil loosening prior to direct drilling alleviated the significant reductions in soil macroporosity, and prevented the increase in soil bulk density, soil strength and percentage water-filled pore space (%WFPS) associated with direct drilling alone. Although soil permeability was optimum under direct drilling alone, the relative increase in %WFPS and reduction in soil aeration were associated with a concomitant increase in common root rot.     

Seasonal differences in tillage draught on a sandy loam soil with long‐term additions of animal manure and mineral fertilizers

Energy requirements for soil tillage are closely linked to soil properties, such as clay, water and soil organic carbon (SOC) contents. Long‐term application of inorganic fertilizer and organic amendments affects SOC content but little is known about seasonal differences in tillage draught requirements of soils subject to contrasting nutrient management regimes. We assessed autumn and spring tillage draught following harvest of early‐sown and timely sown winter wheat grown on a sandy loam in the Askov Long‐Term Experiment on Animal Manure and Mineral Fertilizers. Draught force was related to soil texture, soil water and SOC content, shear strength and bulk density, nutrient management, and yield of the preceding winter wheat. Contents of clay and SOC ranged from 8.9 to 10.6% and from 0.98 to 1.36%, respectively. In the autumn and spring, SOC normalized by clay content explained 38 and 5% of the variation in specific draught, respectively. Specific draught did not differ significantly among individual fertilization treatments. SOC was closely correlated with clay and water contents and bulk density, and with yield of the preceding wheat. Draught force was significantly smaller in the spring than in the autumn. In the autumn when soils were drier (?700 hPa), tillage draught was correlated with several soil characteristics, whereas water content was the dominating parameter in the spring when soils were wetter (?100 hPa). The range of SOC contents observed in this study aligns with that observed in Danish sandy loams under intensive cultivation, and within this range, SOC per se had little effect on draught requirements.     

Effect of tractor weight, depth of ploughing and wheel placement during ploughing in an organic cereal rotation on contrasting soils

The relative effects of using light (2–3 Mg) versus heavier (5–7 Mg) tractors, shallow (15 cm) versus deeper (25 cm) ploughing and on-land versus in-furrow wheel placement during ploughing were investigated from 2003 to 2006 in organic rotations (wheat or barley, green manure, oats with peas) and conventionally fertilized barley. Trials were located on loam soil in south-eastern Norway and silty clay loam in central Norway. Ploughing was performed in spring, when the topsoil moisture content was at or below field capacity, using single furrow ploughs that allowed alternative wheel placement and resulted in complete coverage of the surface by wheels each year (ca. 3 times the normal coverage during ploughing). Low tyre inflation pressures (≤80 kPa) were used throughout. The use of a heavy tractor increased topsoil bulk density slightly in the loam soil, and, in combination with in-furrow wheeling, it reduced air-filled pore space and air permeability at 18–22 cm. On the silty clay loam, the use of a heavy tractor did not increase bulk density, but it reduced air-filled pore space throughout the topsoil. In-furrow wheeling reduced air-filled pore space in this soil also, compared to on-land wheeling. Penetration resistance was in this soil always greater at 15–25 cm depth after shallow than after deep ploughing, especially with in-furrow rather than on-land wheeling. Shallow ploughing led on both soils to marked increases in perennial weed biomass compared to deep ploughing. Earthworms were hardly affected by the treatments, but in the loam in 2006 a higher number of individuals were found where the light rather than the heavy tractor had been used. Few significant treatment effects were found on grain yield and quality. Deep ploughing with a light tractor gave the highest wheat yield and protein content in 2 years on the loam soil, and on the silty clay loam the yield of conventionally fertilized barley was higher after deep than after shallow ploughing. In summary, limited evidence was found to support the use of on-land rather than in-furrow wheeling when ploughing is performed at favourable soil moisture and with tractor weights < 5 Mg. There is, however, reason to be wary of using heavy tractors (>5 Mg), even under such conditions. With regard to ploughing depth in organic rotations dominated by cereals, the need to combat perennial weeds by deep ploughing weighs probably more heavily than any possible beneficial effect of shallow ploughing on stimulating nutrient turnover.     

Prediction of surface runoff and soil loss in southeastern Norway using the WEPP Hillslope model

Yearly and daily surface runoff and soil loss simulated by the WEPP Hillslope model v. 2002.7 were compared with measurements from two different soil erosion plot sites in southeastern Norway. The soil at Bjørnebekk (Bj) was a levelled silty clay loam (2% organic matter) and the soil at Syverud (Sy) was a loam (5% organic matter). The plots at Bj were 21 m long and 8 m wide, while the plots at Sy were 30 m long and 7 m wide. Slope at both sites was 13%. Four management systems for grain production were used: autumn ploughing (AP), winter crop rotation (WCR), autumn harrowing (AH) and spring ploughing (SP). Hydraulic conductivity and soil erosion parameters were determined using WEPP-recommended equations based on measured soil parameters. In general, the WEPP Hillslope model simulated fewer runoff events than measured for all management systems during 1990–1998. Runoff events in winter were seldom predicted and small events (<5 mm) were mostly missed. To use the WEPP Hillslope model on Norwegian soils, where major soil loss events from arable land occur during late autumn, winter and early spring, improvements in winter hydrology calculations are needed. In particular calculations of soil frost development and infiltration into frozen soil need to be improved. The WEPP-recommended soil erosion parameter equations were unsuitable for these two Norwegian soils, especially for levelled soil.     

Tillage effects on cassava (Manihot esculenta) production and some soil properties

Cassava is traditionally grown on tilled soils. Interest in reduced-tillage systems is increasing in the humid tropics due to erosion problems. A field study was conducted on a sandy clay loam Ultisol to compare cassava performance in three tillage systems effects on soil water and organic carbon content. Tillage treatments were: (1) ploughing, harrowing and ridging (conventional); (2) digger-made holes (minimum); (3) pushing the sharpened end of cassavs cuttigs directly into the soil (no-till). Tillage did not affect total biomass yields in the first year. In the second year, significant differences were obtained in the yield of tops but not of fresh roots. No-till and minimum tillage out-yielded the conventional system by 40% and 23%, respectively, in the yield of tops,. It was apparent that elimination of ploughing did not reduce total biomass yield. Soil moisture contents in no-till and minimum tillage were significantly higher (P = 0.05) than in the conventional-tillage system. Conv organic carbon decresed significantly (P = 0.01) over time in all tillage systems. Conventional tillage gave the highest reduction. Cassava may be grown successfully in reduced-tillage systems in Ultisols of the humid tropics.     

Yield and N uptake as affected by soil tillage and catch crop

Two field trials with spring barley (Hordeum vulgare L.) were conducted at two locations in Denmark in order to evaluate the effects of tillage and growth of a catch crop on yield parameters under temperate coastal climate conditions. Ploughing in autumn or spring in combination with perennial ryegrass (Lolium perenne L.) as a catch crop was evaluated on a coarse sand (Orthic Haplohumod) from 1987 to 1992 at three rates of N fertiliser application (60, 90 and 120 kg N ha⁻¹ year⁻¹). Rotovating and direct drilling were also included as additional tillage practices. The experiment was conducted on a 19-year-old field trial with continuous production of spring barley. Ploughing in autumn or spring in combination with stubble cultivation and a catch crop, in addition to minimum tillage, was evaluated in a newly established field trial on a sandy loam (Typic Agrudalf) from 1988 to 1992. Yield parameters and N concentrations in grain and straw were determined. On the coarse sand, N uptake in the grain in ploughed plots without a catch crop was significantly greater when spring ploughed as opposed to autumn ploughed, but grain and straw yields did not differ significantly. Grain yield, straw yield and total N uptake did not differ significantly between direct drilled and autumn ploughed plots, but the trend was for grain yield to be lower with direct drilling. After 19 years of catch crop use, yield parameters in ploughed plots were greater than in plots without catch crops. This was most pronounced in the autumn ploughed plots. Rotovating the catch crop in the spring decreased grain yield compared with underploughing the catch crop in autumn or spring. No significant interactions were found between tillage and N rates. On the sandy loam, grain as well as straw yield and total N uptake were not significantly affected by catch crop or time of ploughing. Grain yield was significantly lower with reduced tillage (stubble cultivation in autumn) than in all other treatments.