Zero-tillage Systems Research Articles

Zero-tillage establishment of alfalfa and meadow bromegrass as influenced by previous annual grain crop

Conventional forage establishment techniques (i.e. preseeding tillage) can result in soil erosion and inefficient water use during the establishment period, and may result in poor plant establishment. Using a zero-tillage (ZT) system may overcome these limitations. The first experiment, conducted under favourable post-seeding moisture conditions, compared establishment, plant development, growth, and dry matter production of alfalfa (Medicago sativa L.) and meadow bromegrass (Bromus biebersteneii Roem and Shult.) under ZT and conventional tillage (CT) following three different annual crops. Significant previous crop × tillage system interactions in both years, indicated that forage crop establishment and dry matter production were lower under ZT than CT when the preceding crop was wheat (Triticum aestivum L.), however, no significant differences were observed when the preceding crop was either field pea (Pisum sativum L.) or canola (Brassica napus L.). Significant previous crop × forage species interactions for crop establishment indicated that while alfalfa was unaffected by previous crop type, emergence of meadow bromegrass was reduced when wheat was the previous crop. Significant previous crop × tillage system interactions for plant development indicated that development of both forage species was temporarily delayed under ZT when wheat was the previous crop. No treatment effects were observed for year after establishment dry matter production. A second experiment, conducted under conditions of post-seeding drought, assessed the impact of spring wheat straw management on establishment of alfalfa and meadow bromegrass under CT and ZT. Superior establishment of both alfalfa and meadow bromegrass under ZT was attributed to higher levels of soil water under ZT. Straw management (removal vs. returned to land) had no effect on either forage species. Results of these studies indicate that ZT is a feasible alternative for establishing forage crops, even where levels of previous crop residue are very high. Key words: Direct-seeding, straw management, wheat, canola, field pea, Haun stage, forage

The effect of KCl, KNO3, and CaCl2 fertilization under conventional- and zero-till systems on common root rot, dry matter yield and grain yield of Heartland barley

Field studies were conducted on two soil types testing low in Clover a 4-yr period to assess the influence of K and Cl fertilization under zero (ZT) and conventional tillage (CT) management on common root rot, dry matter yield at heading, and grain yield of Heartland barley. Tillage did not influence incidence of common root rot in the 4 site-yr where assessments could be taken. Common root rot incidence was reduced by KCl applications in 1 out of 4 site-yr. Dry matter yield at heading and grain yields were consistently higher with ZT than with CT on the silty clay soil, but only in 1988 on the fine sandy loam soil. The higher yields with ZT than with CT may be due to greater moisture conservation under the ZT management system. Response to K or Cl applications was generally not influenced by tillage treatment. Applications of Cl had little influence on either dry matter yield at heading or grain yield, despite the low initial Cl levels in the soils. Application of fertilizers containing Cl, therefore, may not be consistently beneficial, even on soils testing low in Cl. Key words: Potassium, chloride, tillage, barley, common root rot

Nitrogen partitioning and cycling in barley-soil systems under conventional and zero tillage in central Alberta

Cropping systems which conserve soil, water and nutrients are needed on the Canadian prairies. The objectives of this study were: (1) to assess the effects of urea injection on N partitioning in barley-soil systems under conventional (CT) and zero tillage (ZT); and (2) to measure the dynamics of fertilizer and soil N over the growing season. Twelve microplots were installed in each of CT and ZT plots located on a Black Chernozemic soil and were fertilized (59 kg N ha−1) with 15N urea solution, sown to barley (Hordeum vulgare (L.) 'Empress') and destructively sampled at the fifth leaf, ear emergence, grain filling and ripening growth stages. Distribution of 14N and 15N in shoots, roots, mineral N, microbial N, and soil organic N were measured. The recovery of fertilizer N in the soil-plant system was not different between treatments. Microbial N and non-microbial organic N accounted for > 80% of residual 15N in both treatments. Nitrogen budgets showed that grain removal from CT was 76 kg ha−1 and 56 kg ha−1 in ZT. Our study suggests that more 15N from injected urea was converted to organic N under ZT than CT; thus ZT systems have the potential of conserving N. Tillage practices affect the fate of added N. Key words: Typic Cryoboroll, 15N, organic matter, Hordeum vulgare, N recovery, zero tillage

The effects of tillage systems on the economic performance of spring wheat, winter wheat, flax and field pea production in east-central Saskatchewan

The long-term viability of Canadian prairie agriculture depends on the ability to arrest soil degradation caused by wind and water erosion and excessive tillage. The challenge is to develop crop-production systems that are economically viable and environmentally sustainable. The objective of this study was to quantify the short-term economic performance of field pea (Pisum sativium L.), flax (Linum usitatissimum L.) and spring and winter wheat (Triticum aestivum L.) grown under three tillage-management systems. The economic analysis was based on a tillage × crop rotation experiment started in 1986 and involving zero tillage (ZT), minimum tillage (MT) and conventional tillage (CT) and three 4-yr crop rotations. The economic analysis considered only costs associated with purchased inputs and machinery. The effects of method of tillage management on herbicide and fuel use were also determined for each crop. Costs of production were similar for all tillage systems and crop types. Net returns were higher for field pea, flax and spring wheat grown on stubble using ZT and MT than when CT was used, because of higher grain yields. Net returns were similar for winter wheat grown on stubble and for spring wheat grown on fallow for all tillage-management systems. Fuel consumption was highest for CT, intermediate for MT and lowest for ZT for all crops except winter wheat. In contrast, herbicide use was greater for ZT and MT than for CT for al crops except winter wheat; no differences were observed among tillage systems for this crop because it was always seeded directly into standing stubble. The shift from CT to ZT or MT systems did not increase costs of production or reduce short-term economic returns. ZT and MT had higher production potential than CT because increased soil-moisture conservation generally provided higher net returns. ZT used less fuel but more herbicides than MT and CT. Key words: Stubble cropping, fallow cropping, zero, minimum, conventional

Economics of tillage systems for spring wheat production in southwestern Saskatchewan (Canada)

The economic performance of continuous wheat ( Triticum aestivum L.) and fallow-wheat rotations grown under conventional, minimum- and zero-tillage management practices on silt loam, sandy loam and heavy clay in southwestern Saskatchewan was determined during the relatively dry period of 1982–1988. The costs and returns for each rotation-tillage system were evaluated annually based on 1989–1990 price and cost conditions, and for various other plausible scenarios. Gross returns on silt loam were higher for continuous wheat (average 228 $ ha −1) than for fallow-wheat systems (average 155 $ ha −1). On the sandy loam, gross returns were similar for all cropping systems (average 112 $ ha −1); on the heavy clay, they were higher for fallow-wheat than for continuous wheat (139 versus 119 $ ha −1). Conservation tillage management increased gross returns over that obtained with conventional tillage only in years when growing season temperatures were high and precipitation was poorly distributed, or when the 21-month summerfallow period was droughty. On silt loam, gross returns were significantly lower with conservation tillage in as many as 3 of 7 years. On silt loam, net returns were highest for conventionally tilled continuous wheat when wheat prices were> 175 $ t −1; at lower wheat prices, conventionally tilled fallow-wheat was the most profitable. On the other soils, minimum- and zero-tillage fallow-wheat provided the highest net returns at all wheat prices tested, with minimum tillage being slightly better at low wheat prices, but at these sites conventionally tilled fallow-wheat was not studied. The cost of production was highest for continuous wheat and for zero-tillage management. For fallow-wheat systems, conservation tillage required lower expenditures than conventional tillage for fuel, labor, machine repair and machine overheads; costs for minimum tillage averaged 9 $ ha −1 and for zero tillage 15 $ ha −1 lower on the silt loam. These savings were more than offset by increased herbicide costs which averaged 26 and 64 $ ha −1 higher for minimum-tillage and zero-tillage systems, respectively. We concluded that producers in southwestern Saskatchean who are motivated primarily by short-term profit will find little incentive to adopt conservation tillage systems for spring wheat production, unless they are situated on soils that have already incurred severe soil loss or the soils are highly prone to further erosion losses.

Zero-tillage furrow opener effects on seed environment and wheat emergence

Optimum emergence is necessary to attain maximum crop yields, particularly in reduced and zero-tillage systems. However, zero-tillage seeder performance under zero-tillage conditions is not always adequate, and thus may limit potential yield benefits from this soil and water conserving practice. A study was conducted to measure the range of influence of zero-tillage openers on some soil physical properties of the soil-seed environment. Furrow opener design has direct consequences on soil surface disturbance, furrow compaction levels, and post-seeding soil water requirements in the seed row. While soil temperature and wheat cultivar differed between two distinct field trials, furrow opener designs conducive to adequate compaction of seed furrow with press wheels consistently resulted in better wheat emergence, when soil water potentials were not limiting. This study demonstrates that seeding tool design has a quantifiable influence on seed furrow properties, and that this information can be used to develop precise guidelines for future designs of furrow openers and press wheels.

Effect of tillage systems and crop sequence on the rhizosphere microflora of winter wheat

The effect of different soil cultivation intensities on the occurrence of microfungi in the rhizosphere, rhizoplane and roots was studied in a six-course crop rotation using 50% cereals. The experiment was carried out on a chernozem soil at Hrušovany near Brno (Czechoslovakia) in a cereal production area. Winter wheat was grown in conventional-, minimal- (shallow) and zero-tillage systems. The in vitro antagonistic activity of the rhizosphere microflora against Gaeumannomyces graminis v. Arx et Olivier var. tritici Walker was assessed using the biotic effect method. Zero tillage resulted in an increased number of fungal isolates obtained from the rhizosphere and the rhizoplane and a decrease in isolates from the roots, especially at the Feekes growth Stage 10.1 – 10.5. Gaeumannomyces graminis var. tritici was more common under conventional tillage than under the other variants while the reverse was true of Fusarium. The higher antagonistic activity of the rhizosphere microflora under zero tillage conformed with the better visual health of winter wheat plants.

SNOW AND FERTILIZER MANAGEMENT FOR CONTINUOUS ZERO-TILL SPRING WHEAT

In this 3-yr study the effect of snow management, by means of cereal straw trap strips, and fertilizer management (rates of N and P, time and placement of N) on spring wheat (Triticum aestivum L.) yield, N use efficiency, and moisture conservation were examined in a zero-till system on a Brown Chernozemic loam soil in southwestern Saskatchewan. Fall and winter precipitation equivalent to 132, 93 and 68 mm of water was received in 1981–1982, 1982–1983, and 1983–1984, respectively. Efficiency of soil water intake in short stubble was constant at 29% but in tall stubble it was 35, 33 and 65% for the 3 yr. The advantage of water conserved by cereal straw trap strips compared to the standard short stubble treatments averaged 13 mm to the 120 cm soil depth and ranged between 5 mm in 1982–1983 and 25 mm in 1983–1984. Growing season rainfall averaged 244, 176, and 100 mm in 1982, 1983, and 1984, respectively. The use of straw trap strips resulted in greater grain yields than when the straw was cut at one standard height (about 18 cm), the difference being most marked in the driest year. In the two wet years, yields were greater for spring-applied than for fall-applied urea N, and for deep-banded than for broadcast N. In the dry year, fertilizer treatments had no effect on yield. Broadcasting urea in the fall was the least efficient treatment. Yield response to P applied at rates as high as 53 kg ha−1 was only significant in the second year, and even here the response was not large. Grain protein and N use efficiency generally responded in a manner similar to grain yield. Although the moisture conserving advantage of trap strips does not so far support a plausible move to continuous cropping in the Brown soil zone, the yield responses are encouraging and might result in producers making more extensive use of this inexpensive technique.Key words: Wheat, fertilizer placement, fertilizer timing, cereal straw trap strips, zero tillage, snow management

Nitrogen transformations with special reference to gaseous N losses from zero-tilled soils of Saskatchewan, Canada

This paper summarises the work on N transformations under zero-till (ZT) in comparison to the conventional-till (CT) farming system in chernozemic soils of Saskatchewan, Canada. Cumulative gaseous N losses (N 2 O + N 2) measured with acetylene inhibition-soil core technique ranged from 1 to 7 kg ha −1 year −1 N for CT and from 12 to 16 kg ha −1 year −1 N for ZT fields. In both CT and ZT, gaseous N losse were 2–5 times higher for a wheat-fallow than a continuous-wheat rotation. The denser surface soil and consistently higher moisture content of ZT fields were identified as the main reasons for higher rates of denitrification. The potential denitrification rates were markedly higher in ZT and the population of denitrifiers was up to six times higher than in the CT fields. Crop residues doubled the gaseous N losses. Temperature above 5°C did not alter denitrification rates nor did a wide range of mineral N. The contribution of lower soil horizons towards gaseous N losses was negligible. Mole fraction of N 2O [N 2O/(N 2O + N 2)] showed a reverse relationship with soil moisture and varied from 28 to 98% in the total gaseous N products. About 35% of autumn-applied 15N-labelled fertilizer N was lost via denitrification and 7–20% became immobilized by the following spring. Leaching was not responsible for the lower efficiency of fertilizer N. Due to adequate N fertilization and good straw mulch conditions, yield, N uptake and protein content of wheat were highest in the ZT system. The ZT system was also efficient in conserving more moisture from over-winter snowfall and rains.

Spring wheat growth and 15N studies under zero and shallow tillage on the Canadian prairie

Zero-tillage (ZT) farming systems offer the potential of reducing soil erosion and conserving soil moisture on the semi-arid regions of the Canadian prairie. Since changes in soil tillage may alter the soil condition and environment, field experiments were conducted to assess the effect of ZT on spring wheat growth and 15N urea utilization and recovery. The study compared ZT and conventional shallow tillage (ST, 10 cm) systems, of 2–16-year duration, situated on a range of Chernozemic soils. Generally, ZT produced similar grain and straw yields as the ST; incidences of reduced yield under ZT were associated with poor seedling establishment. Characteristic lower soil temperature (1–4°C in seed row at 5-cm depth) under ZT was not related to crop yield, except for reduced early growth at one site. Soil moisture (to 120 cm) was similar between tillage systems, although moisture variations at the soil surface (0–5 cm), associated with differences in surface mulch, were apparent. Plant uptake of P and K was similar between tillage systems. Differences in N concentration, plant uptake of soil and fertilizer N and indices of available soil N between tillage systems over the growing season, tended to be small and did not differ substantially, although site or location differences were evident. Overall N yield was mainly related to the ability of the plant to utilize N for growth and plant yield. Recovery of the fertilizer N in the soil-plant system was not related to differences in soil tillage.

The evaluation of preliminary farming systems technologies: Zero-tillage systems in West Africa

The appropriate form of evaluation of new farming systems depends on the stage of development of the technology. At each state of technology development new systems are screened and the most promising ones selected for further research. Linear programming is a cost-effective tool for the evaluation of preliminary technologies as it allows interaction between the production parameters, quantifies the impact of limiting factors by shadow prices and can also be used for simulation. The screening of potential zero-tillage systems for West Africa is a concrete example.

Selective post-emergence grass weed control in broad-leaf arable crops

With the advent of new selective post-emergence grass killers for broad-leaf arable crops, basic changes in cropping practices are likely to occur. Complete ‘post-em’ weed-control programmes could both accelerate the trend towards close-row and broadcast seeding of, for example, soya, and stimulate the use of reduced-cost band-spraying in established wide-row crops. By selectively controlling problem grasses they should encourage the adoption of reduced or zero-tillage systems.

Weed management: fact or fable?

Weed management is a new term for the age-old practice of employing all available means, in a planned way, to keep weed populations under control. It seeks to distinguish the systematic approach to weed control, based on scientific knowledge and rational strategies, from the pragmatic destruction of weeds. The remarkable efficiency of herbicides has in recent years emphasized the latter and allowed revolutionary methods of crop production to be practised. These have, however, led to serious new weed problems which in turn require more intensive herbicide use. The need for a weed management approach is increasingly recognized. New opportunities for this are provided by the availability of numerous herbicides and plant growth regulators and a growing understanding of the biology, ecology and population dynamics of weeds in relation to crop production systems. Examples discussed include: systematic control of grass weeds in intensive cereals in Britain, weed control in rice and in soybeans, the control of aquatic weeds by biological and chemical methods and an experimental zero-tillage cropping system for the humid tropics based on herbicides, growth regulators and ground-cover leguminous crops. In such management systems, interference of weed behaviour by exogenous growth regulators is likely to be of increasing significance. Constraints on the adoption of weed management practices include lack of support for weed science as a discipline, limited appeal to the agrochemical industry and inadequate extension services in many countries.

The effects of tillage and zero-tillage systems on soil aggregates in a silt loam

Three seedbed preparation systems were compared over the 1973–1974 spring-summer season on a pseudogleyed “Tokomaru” silt loam, on two adjacent experimental sites. Experiment 1 was tilled and left fallow over the winter of 1973, while experiment 2 was left in pasture over the winter. Both areas were then prepared and sown with choumoellier seed by one of the following systems: 1. (1) traditional plough/disc/harrow, sown with conventional field drill; 2. (2) rotary-cultivation, sown with conventional field drill; 3. (3) zero tillage (or direct drilling) after herbicide application (paraquat and Dicamba). As a result of these treatments, the soil which had been sprayed with herbicide and direct-drilled was significantly more resistant to structural damage than the other two treatments as determined by sieving under water. Soil structural stability under the rotary cultivated treatment appeared to decrease to a greater extent than with tillage based on ploughing, as the length of time out of pasture increased. Dry-sieving of soil sample confirmed these effects. The rotary cultivation treatment resulted in the greatest proportion of soil in the smaller aggregate size fraction (less than 1·7 mm dia.) at all sampling dates. The results suggest that the wider use of zero tillage (or direct drilling) techniques and machinery may result in more desirable soil structure being retained under intensive cropping situations.

Efficacy of a Zero-Tillage Cultural System for Asparagus Produced From Seed and Crowns1

Abstract Asparagus (Asparagus officinalis L. Cv. Cal. 711) grown both from seed and 1-year old crowns was maintained in a zero-tillage cultural system for 4 years and compared with that grown in a conventional tillage system. In the first 3 harvest seasons, yields of asparagus produced from crowns were increased 27% in the zero-tillage system. Asparagus from seed yielded as much as that from crowns after the third year, but spear size was appreciably smaller. Paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) in combination with either simazine (2-chloro-4,6-bis(ethylamino)-s-triazine), monuron (3-(P-chlorophenyl)-1,1-dimethylurea), or terbacil (3-tert-butyl-5-chloro-6-methyluracil) provided excellent weed control during each growing season without injuring asparagus. Rotary chopping was a satisfactory method for returning mature brush to the soil. Additional advantages of zero-tillage were a reduction in volunteer asparagus seedlings, improved late season weed control, and less mechanical injury to crowns and buds. This cultural system provided excellent weed control in fields produced by direct seeding where crown depth was shallow and tillage impractical.