Organic farming practices aim to maximise the delivery of ecosystem services in the agricultural landscape. However, in order to maintain optimal crop productivity the mouldboard plough is often used to control weeds and this can have negative effects on a range of soil parameters, thereby jeopardizing delivery of these services. Reduced tillage (RT) can be beneficial to soils and could improve both the efficiency of production and the delivery of ecosystem services on organic farms. However, abandoning the plough on organic farms is challenging due to impaired weed control. Here we report on a two year trial where an RT system with the Ecodyn, with duck feet shares operating at a depth of 7.6 cm in combination with seed drilling, was compared with mouldboard ploughing. Spring oat and spring barley establishment was improved under RT. Weed cover and biomass was greater under RT, but there was no difference in cereal grain yields in either year. The RT system used 71% less fuel and tillage operations took 72% less time that the plough system

Crowley, Oliver

Döring, Thomas F.

Measures, Mark

English

Organic Eprints

Agriculture and the Environment IX, Valuing Ecosystems: Policy, Economic and Management Interactions (2012)  169 USING REDUCED TILLAGE TO IMPROVE THE EFFICIENCY OF ECOSYSTEM SERVICE DELIVERY ON ORGANIC FARMS  O Crowley and TF Döring  The  Organic  Research  Centre,  Hamstead  Marshall,  RG20  0HR,  UK,  E-mail: oliver.c@organicresearchcentre.com  SUMMARY  Organic  farming  practices  aim  to  maximise  the  delivery  of  ecosystem  services  in  the agricultural  landscape.  However,  in  order  to  maintain  optimal  crop  productivity  the mouldboard plough is often used to control weeds and this can have negative effects on a range of soil parameters, thereby jeopardizing delivery of these services. Reduced tillage (RT) can be beneficial to soils and could improve both the efficiency of production and the delivery of ecosystem services on organic farms. However, abandoning the plough on organic farms is challenging due to impaired weed control. Here we report on a two year trial where an RT system with the Ecodyn, with duck feet shares operating at a depth of 7.6 cm in combination with seed drilling, was compared with mouldboard ploughing. Spring oat and spring barley establishment was improved under RT. Weed cover and biomass was greater under RT, but there was no difference in cereal grain yields in either year. The RT system used 71% less fuel and tillage operations took 72% less time that the plough system.   INTRODUCTION   The delivery of multiple ecosystem services is a core principle of organic farming. In pursuit of this goal, organic farming systems incorporate into the landscape functional diversity (at the crop, variety and genetic level) in both space and time. By diversifying crop rotations and avoiding agrochemicals, levels of soil organic matter are often greater, biodiversity is often increased  (Mäder  et  al., 2002) and the  energy  efficiency of the production system  can be greater  on  organic  farms  when  compared  to  conventional  farming  systems  (Chappell  and LaValle, 2011). However, there are costs associated with the delivery of ecosystem services associated with organic farming practices – in particular those associated with the use of soil tillage.   Soil inversion using a mouldboard plough is an effective means of controlling weeds without the need for herbicides, but it can also be associated with negative effects on a number of soil parameters including habitat disturbance of soil organisms, increased losses of soil organic matter and emissions of greenhouse gases (Holland, 2004). On the other hand, negative effects associated  with  mouldboard  ploughing  can  be  compensated  for  with  the  use  of  organic manures and cover crops in organic rotations (Teasdale et al., 2007). Additionally, periods of grass-clover ley that leave the soil undisturbed for up to 4 years of the rotation can increase the density and biomass of soil organisms (Lampkin, 1990; Mäder et al., 2002; Riley et al., 2008).   Nevertheless, there is evidence that reducing the intensity of soil tillage can provide benefits to soil health and could further improve the efficiency of ecosystem service delivery and food production on organic farms (Holland, 2004; Peigné et al., 2007).   Agriculture and the Environment IX, Valuing Ecosystems: Policy, Economic and Management Interactions (2012)  170 Currently, 44% of conventionally farmed arable land in England is cultivated with reduced or zero tillage (National Statistics, 2010). However, this figure is likely to be much lower for organic farms where the adoption of RT presents more of a challenge as numbers of weeds, particularly perennial species, often increase  and persist in  subsequent  cash  crops and  can reduce grain  yields (Peigné et al., 2009). While herbicidal applications allow conventional farmers to control weeds after RT, on organic farms the development of innovative cultural and mechanical approaches to weed control is required to make RT viable.   Here  we  report  results  from  a  two-year  study  conducted  on  an  organic  farm  in  which mouldboard ploughing was compared with the use of a reduced tillage machine. The trial is part of a collaborative EU project (TILMAN-ORG www.tilman-org.net) which brings together results  from  27  trials  comparing  reduced  tillage  with  mouldboard  ploughing  across  10 European countries.  MATERIALS AND METHODS  A  randomized  complete  block  trial  with  three  replicates  was  conducted  over  two  spring growing seasons (2010 and 2011) on an organic farm in Gloucestershire, England (51°39'N, 2°09'W, 142 m). Three fields (average 5.2 ha) on a clay/clay-loam soil were split into two tillage treatments: conventional mouldboard ploughing and reduced tillage. The conventional mouldboard  ploughing  treatment  (hereon  “Plough”)  comprised  of  a  powerharrow  and mouldboard plough at 15 cm soil depth. In the reduced tillage treatment (hereon “RT”) an innovative machine, the Ecodyn cultivator (www.eco-dyn.com), was used to loosen the soil with duck feet shares at a depth of 7.6 cm in combination with seed drilling.    On 14 April 2010 both tillage treatments were drilled with the Spring Oat cultivar Husky at 190 kg/ha. After harvest both treatments were sown with a green manure cover crop mixture of stubble turnips, forage rape and mustard. In 2011 both treatments were drilled with the Spring Barley (cultivar Westminster). Average rainfall during the 2010 growing season was 55.6 mm, and during the 2011 growing season was 45.5 mm. Average air temperature was 12.2°C in 2010 and 11.9°C in 2011.  In 2010 soil cores were taken from six locations across each plot on two occasions. On the second occasion samples were taken from three soil depths: 0-15 cm, 15-30 cm and 30-60 cm. Samples were bulked and air dried before two subsamples were analysed per plot. Organic carbon was determined using the wet oxidation method. Organic nitrogen was assessed using the Kjeldahl method. Phosphorus mg/l was determined according to the Olsen P method and Potassium was determined using flame photometry. Soil data for 2011 are not available.   Percentage  crop  cover,  crop  plant  density  and  ear  density  were  assessed  in  four  0.25  m2 sectioned quadrats in each plot in both years. Weed infestation was measured using the same method of percentage cover and in 2010 dry matter biomass from four 0.25 m2 subplots in each plot was measured. Grain yield was determined by cutting the crop at ground level in four 1 m2 quadrats in each plot, and fuel costs and time to carry out cultivation and seed drilling were calculated  on  each  operation.  All  data  were  analysed  using  one-way  ANOVA  with  the statistical software R, version 2.13.1 (Crawley, 2007).    Agriculture and the Environment IX, Valuing Ecosystems: Policy, Economic and Management Interactions (2012)  171 RESULTS  Crops  In both growing years crop cover after establishment was significantly  greater in RT plots (p<0.01 and p<0.05 in 2010 and 2011, respectively, Table 1). Plant density was also higher in RT plots although the difference was not significant (p>0.05). Ear density in RT was higher by 104 plants/m2 in 2010 (p<0.0001) but similar to plough in 2011.   In 2010 oat straw length was on average 10 cm longer in RT plots (p<0.05) whereas both the straw length and ear length of barley in  2011 were longer in  Plough plots  (8.5  cm  and 2.3 cm  respectively;  p<0.01  and p<0.001).   In both years, the average yield on RT plots was 0.1t/ha higher on RT plots but this difference was not significant in 2010 or 2011 (p>0.05, Table 1).  Weeds  In 2010 weed cover and biomass were  greater in RT plots (p<0.001; p<0.05) in the early season (May) but there was no difference later in the growing season (June) (p>0.05).  In 2011 average weed cover tended to be higher in RT plots in both the early (May) and late (August) season, although neither difference was significant (p>0.05).   Fuel Costs and Man Hours   In 2010 the RT system used 14.02 litres of fuel/ha and took 30 minutes/ha to carry out all operations including seed drilling. The Plough system used 48.18 litres/ha and 108 minutes/ha in man hours. Thus, RT used 71% less fuel and 72% less time than the Plough system.  Soil  In  2010  there  was  no  significant  difference  between  tillage  treatments  for  any  of  the  soil parameters investigated (p>0.05).    Figure 1:  Fuel use and tillage time associated with RT and Plough systems in 2010 0 20 40 60 80 100 120 Fuel useage (l/ha)  Tillage time (mins/ha) Fuel use (l/ha) and Tillage time (min/ha) RT Agriculture and the Environment IX, Valuing Ecosystems: Policy, Economic and Management Interactions (2012)  172 Table 1:   Mean crop cover, weed cover (May) and grain yield in 2010 and 2011    Crop cover (%)  Weed cover (%)  Grain yield (t/ha) 2010              Reduced tillage  29  11  4.3        Plough    6  0  4.2   **  ***  Ns 2011              Reduced tillage  74  7  4.8        Plough    50  0  4.7   *  Ns  Ns ANOVA: ns, not significant, ***P<0.001, **P<0.01, *P<0.05.  DISCUSSION  Dry sowing conditions in both 2010 and 2011 meant crop cover and plant density of spring oat and spring barley was greater in plots treated with RT when compared to those treated with the Plough.  RT  can  improve  the  establishment  of  cereal  seed  as  lower  soil  aeration  promotes moisture conservation and increases in soil organic matter associated with RT can produce soil structural  conditions  conducive  to  improved  infiltration  rates  and  greater  water  holding capacity  (Vakali  et  al.,  2002;  Krauss  et  al.,  2010).  However,  when  soil  moisture  is  not  a limiting factor, weed control may become more important in determining crop performance (Vakali et al., 2002; Peigné et al., 2009). In the present study, dry sowing conditions meant seed sown under the RT system gained an early advantage that outweighed or offset the greater weed pressure found on RT plots later in the season. Longer term trials examining the effects of RT on organic rotations have reported increases in the abundance of weeds along with a change in the community composition to perennial species including competitive grass weeds (Peigné et al., 2007). In the present trial, total weed cover was low in both years and in both treatments  (11% and 6% in  RT plots  and 0% and 1% in Plough plots  in  2010 and 2011, respectively)  suggesting  the  RT  machine  used  in  the  trial  was  able  to  constrain  the  weed population  below  an  economically  significant  threshold,  but  the  composition  of  the  weed community may change over time.  It is planned to continue the experiment for at least 2 more years in order to monitor the weed community.  During the first year of conversion to RT there was no difference in the soil nutrient profiles between tillage systems. Weed infestation and soil moisture were the key factors determining crop  performance.  However,  RT  can  result  in  slower  soil  warming  in  spring  and  delayed mineralisation and supply of nitrogen to crops (Berner et al., 2008). In 2010 straw length was longer and head density was higher in RT plots as a result of improved crop development resulting from greater soil moisture availability during dry growing conditions. In 2011 straw and ear length of barley plants were significantly shorter in RT plots. Although soil nutrient data are not available for 2011 it is likely that the inhibited development of barley grown under RT  is  related  to  a  lack  of  synchronicity  between  supply  and  demand  of  soil  nutrients. Interactions between crop performance and crop type under RT systems have been reported previously (Berner et al., 2008; Vakali et al., 2011). Berner et al. (2008) observed reduced yield  of  winter  wheat  under  RT  but  an  oat-intercrop  was  unaffected  by  tillage  treatment. Winter wheat has a high nitrogen demand early in the growing season and as a result delayed Agriculture and the Environment IX, Valuing Ecosystems: Policy, Economic and Management Interactions (2012)  173 mineralisation after RT can inhibit plant development, whereas nitrogen demand in oats is lower and later in the season so plants are less affected by delayed mineralisation associated with RT. In the present trial neither oat nor barley yield was affected by tillage type; however the shorter straw and ear length observed in the barley crop suggests the plants suffered from delayed mineralisation. Higher ear density in RT plots counterbalanced shorter ear lengths and as a result there was no difference in grain yield between tillage treatments.   Reducing the intensity of soil tillage typically involves a shallower working depth that requires reduced  power  input  and  allows  higher  forward  speeds  that  can  increase  the  work  rate  in comparison  to  ploughing.  The  reduced  tillage  machine  trialled  in  this  study  lowered  fuel consumption by 34 litres of diesel per hectare and decreased by 78 minutes per ha the time to carry out tillage operations while attaining a grain yield comparable to plots treated with the Plough. As a result production efficiency in terms of the ratio of energy in to energy out was improved in RT plots.   Agriculture directly contributes 10-12% of greenhouse gas emission globally; and this figure rises to 30% or more when land conversion and costs beyond the farm gate are added (Smith et al., 2007). Diminishing oil resources and international agreements to reduce emissions of CO2 require innovation in new sustainable technology. RT has become a viable soil management practice for conventional arable production and can be beneficial to soil structural properties and can reduce fuel consumption (Krauss et al., 2010). In the current trial the integration of RT into an organic rotation improved the efficiency of production by reducing the fuel and time to establish a crop while maintaining cereal grain yields and the ecosystem services associated with organic farming.    ACKNOWLEDGEMENTS  We acknowledge the support of David Wilson and Mark Measures and data collection from Jemima Showering. The compilation of results has been achieved in TILMAN-ORG, within the framework of the 1st call on Research within CORE-Organic II, with funding from the UK Government Department for Environment, Food and Rural Affairs.  REFERENCES  Berner A, Hildermann I, Fliessbach DA, Pfiffner DL, Niggli DU and Mäder DP (2008). Crop yield and soil fertility response to reduced tillage under organic management. Soil and Tillage Research 101, 89-96.   Chappell MJ and LaValle LA (2011). Food security and biodiversity: Can we have both? An agroecological analysis. Agriculture Human Values 28, 3-26.  Crawley M (2007). The R Book. 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Reduced tillage effects on soil properties and growth of cereals and associated weeds under organic farming.

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Using minimum tillage to improve the efficiency of ecosystem service delivery on organic farms

Using minimum tillage to improve the efficiency of ecosystem service delivery on organic farms

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