Effects Of Direct Drilling Research Articles

Direct drilling of sugar beet ( Beta vulgaris L.) into a cover crop: effects on soil physical conditions and crop establishment

Direct drilling of sugar beet ( Beta vulgaris L.) into an autumn sown cover crop may reduce field work in spring and environmental damage, such as soil erosion and nitrate leaching, but the balance of its negative and positive effects on crop establishment is unknown. This study compared the effects of drilling sugar beet directly into a cover crop of wheat ( Triticum aestivum L.) or rye ( Secale cereal L.), or after conventional tillage in spring, on soil physical conditions and crop establishment. The experiments were conducted over 4 years in the north of France on three soil types: chalky soil (rendzina), loam soil (calcic cambisol) and silt loam soil (gleyic luvisol). Direct drilling caused less soil compaction than conventional drilling; the wheel tracks for seed bed preparation were made in drier conditions for direct drilling because of the change in tillage time (autumn for direct drilling vs. spring for conventional drilling). Seed bed structure, temperature and water content, and seed placement were very similar for the two drilling techniques (except in the silt loam soil) because of soil tillage done by the sugar beet seed drill and removal of cover crop residues over the sugar beet rows. Final emergence percentage was lower with direct drilling because of predator damage (by skylarks ( Alauda arvensis) and/or field mice ( Apodemus sylvaticus). Seedling growth after emergence was slower with direct drilling. The negative effects of direct drilling on sugar beet establishment may be counteracted by increasing the seed density, or by its positive effects on soil structure and consequently the possibility to sow sugar beet earlier. Because of its environmental advantages, direct drilling of sugar beet into a cover crop is an interesting technique for large farms with heavy work loads in spring in areas where the soil has a high aggregate stability.

Cropping practices in the Victorian Mallee. 1. Effect of direct drilling and stubble retention on the water economy and yield of wheat

Two experiments were conducted at the Mallee Research Station, Walpeup, between 1985 and 1989 to evaluate the impact of conservation farming practices on wheat yields. The first experiment compared wheat crops established by direct drilling into a chemical fallow with those conventionally sown into a cultivated fallow. Over the 5 years, yields ranged from 1.31 to 3.24 t/ha, and there was no reduction in crop yield associated with chemical fallowing and direct drilling compared with the cultivated fallow. There was also no significant effect of the chemical fallow on the amount of water conserved in the soil at sowing, at depth 0-100 cm; the range was 206-274 mm water. The second experiment from 1987 to 1989 examined the effect of maintaining 4 rates of stubble (0, 0.5, 1.0, 2.0 t/ha) on the surface of a conventionally cultivated long fallow. Stubble maintained at 2 t/ha increased the amount of water stored in the soil at sowing, at depth 0-140 cm, by 16 mm in 1 year of 3. This increase in soil water availability was not reflected in increased crop yield. These findings indicate that erosion control and potentially lower production costs associated with direct drilling and stubble retention can be achieved without loss of wheat yield in the Victorian Mallee.

Effects of tillage and lime on Rhizobium trifolii populations and survival in wheat-subterranean clover rotation in southeastern Australia

On strongly acidic sandy clay loams in southeastern Australia there can be problems with the growth and persistence of subterranean clover in clover-ley rotations. During a 4 year rotation, which involved wheat crops and then the re-establishment of clover, the effects of direct drilling and cultivation, and agronomic methods on the nodulation of subterranean clover and the survival of Rhizobium leguminosarum biovar trifolii were compared. In the season in which the clover was sown, the plants on the unlimed soil were poorly nodulated, with no nodules at all on the clover that was sown without inoculation and where the soil had been cultivated. Inoculation of the clover seed increased the nodulation of the clover in the absence of lime. The populations of R. trifolii were estimated throughout the wheat-clover sequence in the rotation. Prior to establishing the experiment the site had been in a subterranean clover-based pasture for 12 years, and the populations of rhizobia were about 200–300 g −1 soil. Without lime the rhizobia populations declined to about 10 or less rhizobia g −1 soil over the period the site was cropped, but where the soil was limed there was no change in the rhizobia populations with cropping. When the subterranean clover was re-established the populations of R. trifolii were increased with all soil treatments, with the unlimed soil obtaining populations similar to those present at the start of the experiment and the rhizobia number on the limed soil increasing to about 10 5 g −1 soil. The most favoured soil environment for R. trifolii was where the pH was raised mostly in the soil surface, and the soil was only minimally disturbed with the direct-drill treatment.

The effects of direct drilling and stubble retention on hydraulic properties at the surface of duplex soils in north-eastern Victoria

Soil hydraulic properties in the sandy clay loam surface horizon of duplex soils were assessed under cultivated, stubble burnt (CCB); direct drilling, stubble burnt (DDB); and direct drilling, stubble retained (DDR) systems for three wheat-lupin rotations, established from 7 to 10 years, in north-eastern Victoria. Disc permeameters were used to determine sorptivity and steady state infiltration in each rotation. A rainfall simulator was used on the 10 year rotation to characterize saturated infiltration and surface soil stability. Cultivation caused an increase in soil bulk density and decreased organic C at the soil surface. Application of a -40 mm water supply potential removed macropore flow from the infiltration process and mainly characterized water flow in the soil matrix. Differences in sorptivity among tillage treatments at this potential mainly reflected initial soil moisture, rather than soil structure. Sorptivity measured on soil cores was related (T = 0.74, P = 0.01)= to sorptivity measured in the field. Under Rainfall simulation , DDR increased sorptivity, wetting depth and time to runoff, and decreased runoff rate and sediment loss, compared with DDB and CCB. Overall, steady state infiltration rate was controlled over time by the permeability of lower soil horizons. The combination of disc permeameter and rainfall simulation measurements provided a useful description of unsaturated and saturated infiltration under field conditions. The DDR system improved the potential for saturated infiltration, maximized rainfall storage in the surface horizon, and increased the stability of macroporous infiltration.

Effects of Direct Drilling on the Phosphorus Uptake and Fertilizer Requirements of Wheat

The effect of direct drilling on the phosphorus (P) relations of ~vheatw as examined in seven field experiments over three years. Compared with conventional cultivation of the soil, direct drilling concentrated available phosphorus nearer the soil surface and resulted in higher strength and lower root length in surface soil (0-10 cm). Tissue-P concentration and dry weight of young plants (< 10 weeks) were consistently lower after direct drilling. It appeared therefore that direct drilling limited the uptake of soil phosphorus. An unknown factor also reduced plant dry weight per unit of P taken up in some experiments, whilst high rates of P fertilizer generally failed to give equal P concentration or dry weight in early growth. It is suggested that the young plants were unable to exploit fully the banded fertilizer because of insufficient adaptation of roots to the concentrated source of P and that this effect is a greater disadvantage for a direct-drilled crop. Direct drilling gave lower grain yields in four experiments when no fertilizer was applied, but where rates of P fertilizer were high, the two tillage treatments produced equal'pields. In these four experiments direct-drilled crops needed more fertilizer to attain 90% of the maximum yield. Crops in cultivated soil had the higher dry weight at anthesis and therefore the higher potential yield at equal rates of P fertilizer (in two years), but they failed to realize their potential at high rates of fertilizer because their greater vegetative growth led to increased water stress after flowering.

Reduced early growth of direct drilled wheat in southern New South Wales: causes and consequences

In five experiments with wheat over 4 years on a red earth soil in southern New South Wales, direct drilling reduced plant population by an average of 15% and individual plant dry weight at 10- 11 weeks by an average maximum of 33% compared with sowing into a cultivated seed bed. The maximum reduction in dry weight per unit area averaged 44% (at tillering), but compensatory growth reduced this to 17% by anthesis. Time to emergence was not reduced and differences in plant weight soon after emergence were very small, which suggests that the effect on plant growth occurred only after emergence. Effects of direct drilling on soil surface (0- 10 cm) temperature and water content were not important factors reducing plant population or early growth but high soil strength seemed the most likely cause of reduced root extension in the direct drilled seedbed (0-1 5 cm). Reduced root extension had no direct effect on plant water relations or nitrogen concentration in leaves, but there was a small effect on phosphorus concentration. Reduced root growth appears to reduce shoot growth but the mechanisms require further study. The reduced shoot growth led to reduced preanthesis water-use. After anthesis direct drilled crops generally used more water and had higher leaf water potentials than crops in cultivated soil, leading to yield increases in 2 of the years with dry spring conditions. Only in a drought year (1982) was there evidence of direct drilling reducing the maximum depth of rooting and therefore reducing total water-use resulting in lower grain yield (8%). Overall, direct drilling increased grain yields by 2.4% (2.514 v. 2.576 t/ha) compared with conventional tillage, despite the large reduction in early growth.

The effects of direct drilling, shallow cultivation and ploughing on some soil physical properties in a long-term experiment on spring barley

SummaryPhysical measurements were made on the soil of a long-term cultivation experiment comparing direct drilling, tine cultivation and mouldboard ploughing for spring barley to investigate possible reasons for differences in yield. The soil was a typical argillio brown earth, approximately 90 cm of sandy clay loam topsoil and clay loam subsoil overlying magnesian limestone. For the three periods 1971–4, 1975–7 and 1978–80 the mean grain yields were marginally lower after direct drilling than after shallow cultivation or ploughing. There was an average decline in yield of 1·33 t/ha from the first to the last period, the decline being greater for direct drilling than the other two tillage systems. Although the surface horizon (0–5 cm) of direct-drilled soil had a higher content of organic matter than the ploughed, this did not increase the stability of the aggregates. Slaking tests had shown the soil to be inherently unstable and likely to suffer from structural problems. After the first 3 years bulk density of direct-drilled soil (0–15 cm) increased markedly toca.l·5 g/cm8and then remained relatively stable. In the ploughed soil, density increased steadily over the period to an average value of co. 1·45 g/cm8. Tine cultivation to 7–8 cm reduced cone resistance values in the surface compared with direct-drilled soil but below 15 cm there were no significant differences. Ploughing gave significantly lower values than direct drilling to a depth of 30 cm. Measurements of pore sizes in direct-drilled and ploughed soil were highly variable with few significant differences. Mean air capacity values (1978–80) tended to be lower in direct-drilled than in ploughed topsoil particularly for plots direct drilled after 7 years of deep tine cultivation. A limited number of root measurements in 1978 and 1980 showed that the length of root per unit of ground area was much less after direct drilling than after ploughing. Shallow cultivation, surprisingly, gave most root with a greater proportion of the root system below 20 cm than in the other two treatments. The classification of this soil according to its suitability for direct drilling cereals is discussed.

The Effect of Direct Drilling and Minimal Cultivation on Earthworm Populations

(1) Earthworm populations in direct drilled and ploughed plots were assessed twice annually for 5 years in a continuous cereal experiment at Woburn. (2) In two other experiments, on continuous cereals at Rothamsted and Boxworth, populations of earthworms were assessed twice annually from the fourth to eighth years of cropping. The cultivations compared were deep ploughing, chisel ploughing and direct drilling. (3) Populations of the deep burrowing earthworms Lumbricus terrestris and Allolobophora longa became much greater in direct drilled than in ploughed plots and, after 8 years of direct drilling, were 17.5 and 37.3 times more numerous than in ploughed plots, at Boxworth and Rothamsted, respectively. Populations of deep burrowing species in chisel ploughed plots were intermediate between those in direct drilled and ploughed plots. By contrast, differences between populations of the shallow working earthworms A. caliginosa and A. chlorotica were much less, the greatest increase in direct drilled plots over ploughed ones being 3.4 times. (4) A survey on Lee Farm in Sussex, of earthworm populations in seven fields that had been direct drilled with cereals for several years and seven fields that had been ploughed and sown with cereals, showed significant differences in populations of L. terrestris and A. longa between ploughed and direct drilled fields but not of A. chlorotica or A. caliginosa. (5) There were significant negative correlations between populations of L. terrestris and A. longa and between those of A. chlorotica and A. caliginosa in the survey.

Stability and organic matter content of surface soil aggregates under different methods of cultivation and in grassland

The effects of direct drilling, shallow and deep tine cultivation, ploughing, and of growing and permanent grass sward on the stability and organic matter content of surface soil aggregates were studied on a range of soils in Southern England. Cultivation treatments were applied continuously for 4 to 6 years. Generally, relative aggregate stability, assessed by turbidimetric and wet-sieving techniques, was enhanced by direct drilling and other forms of simplified cultivation compared with ploughing. Increased stability was associated with increased organic matter status and was not pronounced under grass. In the case of a soil which was previously under permanent grass stability and organic matter content declined after direct drilling but significantly less so than after mouldboard ploughing. Differences in aggregate stability were detected in some soils only after modifying the test procedure and it appeared likely that the magnitude of differences were variable within a season and were related possibly to the tilth forming properties of the soils.

The growth and yield of winter cereals after direct drilling, shallow cultivation and ploughing on non-calcareous clay soils, 1974–8

SummaryThe effects of direct drilling, shallow cultivation and ploughing on the growth of winter cereals (wheat and oats) are reported for the first 4 years of long-term experiments on two non-calcareous clay soils (stagnogleys), representative of soils occupying a large proportion of the cereal growing area of the U.K. These 4 years have been characterized by extreme contrasts in rainfall and wetness of the soil.On a Lawford series soil, with 35% clay, although the treatments affected average grain yields none of the differences was large. With additional nitrogen fertilizer, the yield after direct drilling was significantly heavier by 6% than after ploughing. On the Denchworth series, with 50% clay, 4 year average yields were also similar after direct drilling and ploughing, but in individual years the treatments had large effects. In two wet years grain yields after direct drilling were 89 and 82% of those after ploughing, but in another year they exceeded by 16% those after ploughing, where lodging had restricted grain filling. In the unusually dry season of 1975–6 yields of winter wheat after direct drilling exceeded those after ploughing (by 14 and 6% on the Lawford and Denchworth soils respectively) and this was attributed to greater availability of water and deeper rooting in the spring. In a year of heavy wheat yields (1977–8) about 10t/ha was achieved on both soils irrespective of the method of cultivation. In this year, after prolonged wet soil conditions in winter, the response to additional nitrogen fertilizer was greater after direct drilling and shallow cultivation than after ploughing.The concentration of nitrogen in the crops tended to be smaller throughout the growing season after direct drilling than after ploughing, especially on the Denchworth soil in the wettest season. The method of cultivation had no effect on the uptake of either phosphorus or potassium except on the heavier soil in the wettest year, when potassium uptake was restricted after direct drilling.The results are discussed in relation to information on soil conditions and root growth also being obtained in these experiments.

Effects of direct drilling and shallow cultivation on the nutrient content of shoots of winter wheat and spring barley on clay soils during an unusually dry season

AbstractThe uptake of phosphorus, potassium and nitrogen by winter wheat and spring barley grown after direct drilling, tine cultivation and ploughing on three clay soils has been examined during the driest season since meteorological records commenced in England. The concentrations of phosphorus and potassium in shoots were little affected by the method of cultivation, in spite of the concentration of these nutrients in the surface layers of the soil following direct drilling. The nitrogen concentration was lower in the early stages of growth of winter wheat after direct drilling or shallow cultivation, but not subsequently nor at any stage in spring barley.

Effects of direct drilling and ploughing on root distribution in spring barley, and on the concentrations of extractable phosphate and potassium in the upper horizons of a clay soil

AbstractA comparison was made between the effects of three consecutive years of either direct drilling or ploughing, on the distribution of extractable soil phosphate and potassium, and the distribution of roots of a spring barley crop in the upper 20 cm of the soil. Samples were collected from a clay soil (Evesham series) in June 1975 when the crop was mid‐way through the phase of stem extension (Feeke's growth stage 7–8). With ploughing, the concentration of nutrients was approximately uniform to the maximum depth of cultivation (20 cm). With direct drilling there were markedly higher concentrations of phosphate and potassium in the upper 5 cm of the soil, but at depths between 10 and 20 cm the concentrations of potassium, and particularly phosphate, were lower than with ploughing. Root weight and length, per unit soil volume, in the upper 5 cm, were also greater with direct drilling than with ploughing. However, the more superficial distribution of phosphate and of roots with direct drilling did not restrict phosphate uptake by the crop, despite the dry summer. The results are discussed in relation to factors contributing to differences in the distribution of nutrients and roots in land receiving contrasting cultivations, and possible consequences for crop growth are indicated.

Effects of direct drilling on the soil fauna

Numbers of most species of invertebrates were greater in the soil in which direct-drilled crops were grown. Attacks by slugs and wireworms were much less serious after ploughing. Attack by stem-boring fly larvae tended to be greater in crops in ploughed soil than those direct drilled where cereals were grown continuously. Numbers of Lumbricus terrestris were 2 to 5 times greater with direct drilling than with ploughing but numbers of other species differed much less.

Effects of direct drilling on soil conditions and root growth

Direct drilling affects the pore size distribution in the soil, the distribution of organic debris on and within the soil, and the soil structure. These changes in turn affect the development of the root system of the crop, with consequential changes on its nutrient supply and early growth.

Effects of direct drilling and reduced cultivation on soil conditions for root growth

The two aspects of soil conditions and root growth in reduced cultivation systems are reviewed. Generally, an uncultivated soil is characterized by increased mechanical strength, reduced porosity greater moisture, more organic matter and structural stability at the surface, more earthworms and the development of nutrient gradients. Effects on root growth are much more variable and reflect the indirect relationship that exists between bulk soil properties and root growth.