Benefits of VRA technology for potato production based on Mole soil maps

Transcription

1 Benefits of VRA technology for potato production based on Mole soil maps Eddie H. Loonstra 1 * 1 The Soil Company, Leonard Springerlaan 9, Groningen, 9727KB, The Netherlands *Corresponding author. loonstra@soilcompany.com Abstract In the north of the Netherlands farmers experimented with VRA technology for potato production in three precision farming projects. Two projects focussed on variable planting distance seed potato production, as clay content of soil is heterogeneous. The Mole clay maps served as base for the VRA. The application was applied with adjusted belt planters and data was collected over a period of 4 years. The benefits of this application were on average very good. The production of best paid tubers improved leading to an improved financial yield of 240 euro and more. In the third project starch potato farmers tested the merits of VRA technology for fertilization and disease control of nematodes on sandy soils. A potato harvester with weighing cells was available to map the yield at high resolution with GPS. It was concluded that VRA technology did not result in improved profit for the starch potato production. However, new insights were gained on the effectiveness of pesticides. All 3 projects showed that VRA technology is ready for use and can add value to the farmer s production or can bring in new knowledge. Key words: Mole soil sensor, precision farming, potato production. 1. Introduction Precision farming allows a farmer to apply a differentiated crop management that is fully supported by technology. A farmer is in need of information to base his management decisions on for this differentiated approach. Data of crop, soil or climate -in time and spacecan serve as input for this decision making process. Several sensor systems (remote and proximal) have been developed and tested in this respect (Adamchuck, 2010). In the Netherlands, the possibilities of high resolution mapping of soil properties with a proximal gamma ray sensor have been tested by farmers interested in precision farming. This passive soil sensor system, called the Mole, is capable of measuring the gamma ray energy emitted by top soil and rocks on-the-go (Egmond, 2008). Name: Farmer N Field: Near Farm Size: 8 ha Projectie: Clay content Average: Clay content (% < 2 micron) FIGURE 1: The Mole attached at the back of a quad and a Mole clay map Gamma ray sensors like the Mole measure the energy spectrum from 0 to 3000 kev of the radiation that reaches the surface. In general, 95% of the measured radiation originates from

2 the top 30 cm of the soil. With the Mole high resolution digital soil maps can be constructed of physical soil properties such as clay, organic matter, loam and grain size (Loonstra, 2008). In several precision farming projects in the northern part of the Netherlands, potato farmers developed applications and subsequently tested VRA technology for their main crop based on these high resolution soil maps. 2. Methods 1.1. Sites In the period 2002 up to precision farming projects in the north of the Netherlands have tested the possibilities of VRA technology based on Mole maps for potato production on their farms. Two projects that both lasted 4 years, were situated along the coast line (latitude ). The soils are characterized as light to modest heavy clay and are very heterogeneous within field due to the process of land reclamation. Over 20 farms participated in these projects. The production of seed potatoes is the main activity. The 2 seed potato projects practised precision farming on approximately 600 ha. The main target for the seed potato production is to grow as many tubers in the size 28/55. This size is paid best (Loonstra, ). At the same time another precision farming project was set up in the border area of the northern Dutch provinces Groningen and Drenthe (latitude , longitude ). The soils in this area are from origin peat soils, but due to heavy cultivated turned into sandy soils. The organic matter can vary within field from 5 to 25%. Ten farmers participated in this precision farming project that lasted 3 years. The main crop is starch potatoes and the project covered approximately 300 ha (Egmond, 2009) VRA technology The main target for the seed potato farmers is to grow as many tubers as possible in the best paid size (tuber sizes 28/55). It is known that the growth of potatoes is influenced by the amount of available water in soil. Tubers remain smaller on sandy parts and grow larger on heavy clayish soils. The infield difference in clay content is considered to be the main factor related to water availability in soil. Organic matter content varies little. A differentiated plant distance policy was formulated based on clay content. This allows potato plants to grow in comparable soil conditions with regard to available water. For this purpose the Mole derived clay map was divided into 3 or 4 management zones. A plant distance was chosen for each zone and the map was turned into a VRA map in shape format. The commonly used Miedema Structural belt planter was adjusted for this precision farming application. The terminal of the device was made suitable for processing incoming messages from a GIS. A PDA connected to a GPS and running the VRA map in Farmworks software provides the input for the terminal of the planter. Half of the field was planted with VRA technology. The other half was planted regularly. The harvest of both halves was stored separately. At the end of each growing season several 5m 2 areas were harvested by hand to count the number of stalks and potato tubers. FIGURE 2: Structural variable belt potato planter.

3 > <5000 Opbrengst naar gewichtsklasse 0.00% 5.00% 10.00% 15.00% 20.00% The main target for starch potato growers is to maximize yield in terms of tons per hectare. The main management issues for starch potato production are optimization of fertilizer input and disease control. The organics content varies greatly within field, causing large differences in natural available nitrogen levels during the season. The Mole derived soil organic matter content map was used to construct nitrogen application maps. Two types of fertilization machines were applied; a centrifugal spreader by Amazon and a sprayer by Agrifac with Teejet terminal. In both cases, a PDA connected to a GPS and running the VRA map in Farmworks software provided the input for the terminals of the machines. Half of the field was treated with VRA technology. The other half of the field was regarded as control and fertilized commonly. The project also looked at the possibilities of precision farming for disease control. It was expected that populations of nematodes appear in areas where soil is characterized by high sand content, low organic matter content and low ph. Nematode samples were taken at significant spots at the fields based on the Mole derived soil maps for sand and organic matter content. In addition, in the last year of the project the effects of disinfecting chemical products were analyzed. The fields were divided in more or less comparable areas and subsequently treated with either no product or fully. In two fields 50% treatment was added to this strategy. The project used a specific Grimme harvester to analyze the effects of the trials on the potato yield. This harvester was prepared with weighing cells, a data logger and a GPS for continuous monitoring of yield. Finally, yield maps were constructed and the effects of the trials (variable fertilizer application and disease control application) were statistically analyzed Name: Farmer N Field: East Size: 12.9 ha Projection: Yield starch potato Average: 31.7 Total yield: 409 ton Yield (ton/ha) FIGURE 3: Grimme potato harvester with weighing cells and yield map. 3. Results In order to compare the effects of variable planting distance the yield of the treated and nontreated parts were compared for all fields and combined. The yield was subsequently calculated per hectare. Regular planting distance TABLE 1 Yield data seed potato Variable planting distance kg/ha % kg/ha kg/ha 28/55 % kg/ha kg/ha % kg/ha kg/ha 28/55 % kg/ha 2004, n= , n= , n= , n= average , , The table shows that overall the total yield and the yield of the kg/ha tubers in the size 28/55 was higher compared to the regular planting strategy. The overall results over 4 years show an increase in yield of 4%. No significant differences were found for the different species that were planted. The general financial benefits of the improved yield were calculated to be 241 to 300 euro per hectare (Loonstra, ). The break-even point for this application was calculated to be 9 hectare, as is demonstrated in the table 2.

4 TABLE 2 Break even point VRA variable planting Cost Total investering Annual cost 1. Adjustment Structural planter (depreciation 5 years) 610,- 2. Investment computer hardware (depreciation 3 years) 633,- 3. Assembly 750 (depreciation 3 years) 250,- 4. Investment GPS (depreciation 3 years) 423,- 5. Soil maps 110,- per hectare 28,- (depreciation 4 years) 6. Total annual costs Yield increase per ha Break even point ( )/(7-5) 8.99 ha A more detailed analysis of the results demonstrated that the variable planting strategy was more effective on clayish soils and less on sandy soils. The effects of variable planting were poor on soils with a clay content below 15%. The field trials also showed that fields with broad management zones, hence more variation in clay content, performed better compared to tighter management zones. VRA s that were constructed with management zones of at least 5% clay variation performed best. The amount of variation of the planting distance was also analysed. It turned out that a planting strategy varying 80 to 120% performed better compared to a strategy of % variation. The number of stalks and potato tubers were also object of study for this VRA technology. The general assumption is that the number of tubers per m 2 is dependent of the number of stalks per m 2. This assumption could not be confirmed with the outcome of the trials. No correlation was found between stalks and tubers. The results of the VRA trials in the starch potato area were analyzed with the continuous yield maps. It turned out that applying granular fertilizers with VRA technology had no positive yield effect. The yield did not improve and no costs were saved. Small yield improvements occurred in applying the liquid fertilizers with VRA technology. The yield maps were also used to calculate the financial benefits of differences in nematode control strategy. The analysis compared the zero application, the full advised amount of granular products and the 50% treatment. None of the utilized strategies resulted in a significant yield change, whereas significant lower yields were expected in the areas with 50% or no treatment. On average the additional costs of the chemicals exceeded the financial loss of the potato yield. TABLE 3 Yield in kg/ha pesticide trials field 100% 50% 0% 1 54,200 50, ,145 48, ,332 47, ,894 54,964 56, ,056 52, ,643 52,744 50, ,575 49, ,878 50, ,816 53, ,634 44,777 average 51,504 53,854 50, Conclusion The 2 projects that tested the VRA technology for variable planting of seed potatoes demonstrated that the technology is suitable to be applied in daily practice. In general variable planting is considered to profitable. It supports the target to improve the production of tuber sizes 28/55. The best effects were realised on fields with a clay content that varies at least 10% or more and where management zones were constructed for each 5% clay

5 content. Although the optimum variation in planting distance is yet unknown, the 20% variation in planting distance has demonstrated to provide better results then the 10% variation in planting distance. The starch potato project concluded that no correlation was present between the soil properties ph, sand and organic matter content and the number of harmful nematodes. It was also concluded that no significant yield effects occurred using different chemical treatments. After which one can conclude that the profitable use of these pesticides is rather questionable. The results do not justify a VRA related strategy for nematode control for these soils. The project also demonstrated that the yield effects of VRA technology for nitrogen fertilization are limited. In general, despite the positive effects of VRA-technology being demonstrated none of the participating farmers decided to invest in equipment and adopt the precision farming principles. It is concluded that other factors then financial benefits should be fulfilled in order to make precision farming part of the daily agricultural management. Reference list Adamchuck, V.I., Rossel, R.A. Viscarra, Development of on-the-go proximal soil sensor systems. In: R.A. Viscarra Rossel, A.B. McBratney, B. Minasny (Eds.), Proximal Soil Sensing. Progress in Soil Science. Springer Netherlands, pp Egmond van, F.M., Loonstra, E.H. and Limburg, J. (2008). Gamma-ray sensor for topsoil mapping: The Mole. 1 st Global workshop on High Resolution Digital Soil Sensing & Mapping, 5-8 February 2008, Sydney Australia. Egmond van, F.M. (2009). Statistische analyse proeven Precisielandbouw Oost-Drenthe, Report The Soil Company, 23 January Loonstra, E.H. (2008-1). Resultatenrapport variabel poten TSC, Report The Soil Company, 17 January Loonstra, E.H (2008-2). A Mole collecting fingerprints: A gamma ray sensor for measuring physical properties of top soil, IAMFE Conference Denmark, 30 June-3 July 2008, Aarhus Denmark. Acknowledgements The 3 described precision farming projects are partly funded by the EU and Leader+.