GROWTH PREDICTION DEVICE FOR PLANTS

Abstract: The invention relates to a growth prediction device for prognosticating the need for weed control and/or for supplementary fertilization, which device comprises a growth prediction box of a cover material permeable to light, the device having an open bottom (4), comprising a roof (1) and a wall or walls (2, 3) and being provided with ventilation apertures (5). The invention also relates to methods wherein the growth and development of weeds and/or cultivated plants are monitored with the help of the growth prediction device and the correct time for the use of a control substance in terms of weed control and/or the correct time for supplementary fertilization in terms of the growth of the cultivated plants is prognosticated.

Description: Growth prediction device for plants The invention relates to a plant growth prediction device by means of which it is possible to monitor the growth and development of plants, to prognosticate the need for plant protection steps, and to estimate the use of correct and sufficient active agents in terms of the weed flora and to estimate the amount of nutrients released from the soil, for example soluble nitrogen in the soil, a piece of information with the help of which the amount of supplementary nitrogen fertilization in cultivation can be timed and made precise. The invention also relates to methods using the growth prediction device according to the invention. Cultivation is an entity made up of many steps. Achieving a high yield level presupposes correctly timed and effective performance of these various steps and taking into account the plant species specific requirements. Herbicide treatments and supplementary fertilizations constitute a part of this entity. Plant protection is based on planning that exploits the experience and information of previous years regarding cultivation, pests and weeds. The selection of a herbicide and its amount used, as well as the selection of the correct spraying time, are affected by several factors, such as the weed to be controlled, its degree of growth, the plant being cultivated, its degree of growth and the condition of the plant stand, the type and moisture content of the soil, as well as weather factors, such as great temperature variations, a heat wave, night frost, a long rainy season, or drought. Of the 600 species of weeds in Finland, 60 are classified as very harmful and 100 as rather harmful. The most common weeds appearing in cultivated fields in Finland include couch grass, wild oat, pigweed, goutweed, creeping thistle, and scentless mayweed. In addition to seeds, weed plants have many other propagation means, such as rootstocks, runners, tubers, root-collar shoots, and bulbils. The manufacturers of herbicides issue cultivar-specific/weed-specific instructions relating to the dosage and time of use; however, on the basis of these instruction it is not possible to implement, as required by the current legislation or EU environmental subsidies (Ruiskuttajan kasikirja, Finnish Ministry of Agriculture and Forestry, 1996), responsible spraying of a control substance, safe for the environment, nature and the user, at the field segment level. Farm-specific reduction of the amount of control substances used presupposes continuous monitoring of the plant stands and the utilization of both a warning service and control thresholds. As regards plant diseases and noxious insects, the need for control steps can already be prognosticated, but not as regards weeds. The economical threshold of control steps is achieved when it can be estimated that the value of the crop losses caused by weeds will be higher than the costs incurred from their control. In addition to the abundance of weeds, also the weed species affects the threshold value, which varies widely. The threshold per weed plants/m 2 is, for example, 1 plant/m 2 for bedstraw, 25 plants/m 2 for hemp nettles, and 45 plants/m 2 for pigweed. According to present-day practices, the success of weed control can be assessed retrospectively, and the knowledge and experience gained cannot be exploited until the subsequent growing season. A spraying window, i.e. a zero square, has also been used for help in assessing the success of control steps. By a spraying window is understood a small area in the field, not treated with control substances. The spraying window provides information regarding the quantities and species of weeds and regarding any changes that have taken place in the weed plant stand during the growing season. This information, also, cannot actually be exploited until the subsequent growing season. From publication JP-A-5284850 it is known to predict the occurrence of disease, pests and weeds in a lawn at an early stage, the purpose being to optimize the use of control substances and fertilizes in order to maintain the lawn in good condition. In this known method, a sample is taken from the lawn with the help of a test tube, which sample is then taken into a closed thermostatic chamber. The sample is cultured in this chamber for 1-3 weeks in temperature, humidity and solar radiation conditions corresponding to the average conditions prevailing 1 - 6 months after the taking of the sample. The state of the sample is followed up during the culturing period, and thereafter and on the basis of this follow-up, the need, type and amount of pesticides or fertilizers to be applied to the lawn are determined. For purposes of monitoring balanced plant nutrition, many laboratories are specialized in analyzing plant and soil samples, one example being soluble nitrogen in the soil, and in issuing nitrogen fertilization recommendations on the basis thereof. As a procedure the said practice is slow, since sending samples to the laboratory, the analysis of the results, sending the results back to the cultivator, and making the fertilization decision on the farm take a great deal of time, during which the situation in the field may change greatly. Attempts have been made to eliminate the time delay by developing meters by means of which it is possible in the field to measure directly the nitrogen state and nitrogen contents of the plant stand. The nitrogen status of plants has been measured with color reaction paper (ammonium and nitrate nitrogen). With various portable laboratory kits it is possible to measure the nitrogen status of plants and the soil in the field (Pulkkinen 1999). Portable meters have been developed, for example, for measuring the greenness, i.e. chlorophyll, of a plant stand (Watenabe et al. 1980) and the nitrate concentration in sap (Scaife and Stevens 1984). The latest systems are sensors installed in tractors, and plant stand quantity and nitrogen analyses made from aerial and satellite photographs (Wollring et al., 1998; http://www.casecorp.com/agricultural; Grandzinski et al., 1998). Even though a real-time result indicating the need for nutrients is obtained by the above-mentioned methods, releases of nutrients at a time after the measuring time still cannot be prognosticated by the known methods. The present invention, which relates to a plant growth prediction device, provides a simple and inexpensive method for the monitoring of weed growth and development, and it helps in prognosticating the coπ-ect time for weed control and both qualitatively and quantitatively appropriate use of active agents. Likewise, the present invention provides a simple and inexpensive method for monitoring the growth and development of cultivated plants and helps to prognosticate, in terms of the growth of the plants, the correct time and the supplementary fertilization appropriate both qualitatively and quantitatively. According to the invention there is thus provided a growth prediction device for prognosticating the need for weed control and/or supplementary fertilization, which device comprises a growth prediction box made up of a cover material permeable to light, the bottom of the box being open, .and the box comprising a roof and a wall or walls and being provided with ventilation apertures. The said roof and wall or walls delimit the growing space. The growth prediction device according to the invention preferably also comprises a thermometer measuring the temperature inside the box and measuring the temperature outside the box, and possibly a sensor measuring relative humidity and/or some other sensor. The structure of the growth prediction box may have a throughput or some other fastening means for fastening the thermometer measuring the inside temperature of the box and measuring the outside temperature of the box, and possibly a sensor measuring relative humidity and/or some other sensor. The said thermometer and the sensor possibly measuring relative humidity and/or some other sensor preferably constitute part of an automatic data collection unit. The roof and wall material used for the growth prediction box according to the invention can be a conventional greenhouse cover material, such as glass or plastic. The growth prediction box according to the invention may be in shape, for example, a rectangular box or a cylindrical box, in which case the cylinder mantle forms the said wall. According to the invention there is also provided a method for monitoring the growth and development of weeds and for prognosticating the correct times and qualitatively and quantitatively optimal use of active agents in terms of weed control, the method comprising the following steps: a) a growth prediction box of a cover material permeable to light, the bottom of the box being open, and the box comprising a roof and a wall or walls and being provided with ventilation apertures, is installed on the plantation; b) the temperature both inside and outside the growth prediction box is measured daily, and the 24 h heat summation is determined; c) the critical heat summation in the growth prediction box is determined for the time at which the weeds have reached a stage of growth advantageous in terms of weed control; d) the active agent and amount of the control substance are optimized on the basis of the weed data from the growth prediction box; e) the time at which the critical heat summation will be reached outside the growth prediction box is determined, and a weed control spraying is performed. According to the invention there is additionally provided a method for monitoring the growth and development of cultivated plants and for prognosticating, in terms of plant growth, correctly timed, both qualitatively and quantitatively optimal supplementary fertilization, the method comprising the following steps: a) there is installed in the plantation a growth prediction box of a cover material permeable to light, the bottom of the box being open, and the box comprising a roof and a wall or walls and being provided with ventilation apertures; b) the temperature is measured daily inside and outside the growth prediction box, and the 24-hour heat summation is determined; c) the critical heat summation in the growth prediction box at a stage of growth advantageous in terms of supplementary fertilization is determined, and soil and/or plant samples intended for nutrient measurement are taken both from the growth prediction box and from outside it; d) the results are compared on the basis of the analysis results and the heat summation differences in the growth prediction box and outside the box, and a decision is made regarding the need for supplementary fertilization, its amount and time. In the growth prediction box, in growing conditions advantageous in terms of the temperature and the humidity, both cultivated plants and weeds germinate and the seedlings grow faster than in the field outside the box. At the first stage, the weeds growing in the box are identified, the frequency of occurrence of the species is determined, and the control substance or mixture of control substances is chosen. At the next stage, the time of control substance application is specified on the basis of the heat summations determined inside and outside the box. Respectively, the release of nutrients in the soil in a form usable by plants takes place more advantageously in the box at the tilling depth than in the field. At the first stage, soil and/or plant samples are taken from both inside and outside the box, analyses are made either in a laboratory or by a rapid method in the field, the results are compared, and the time and amount of supplementary fertilization, for example, nitrogen fertilization, is specified on the basis of the differences between the growth degree and/or heat summations inside and outside the box. The invention is described below in greater detail with reference to accompanying Figure 1, which shows a perspective view of one growth prediction box according to the invention. According to the embodiment depicted in Figure 1, the growth prediction box is formed by four sidewalls 2 and 3 of fixed size and a roof sheet 1, which are of any material conventionally used as the cover material of greenhouses and permeable to natural light. The bottom 4 of the box is open. The sidewalls have the necessary number of ventilation apertures 5. In addition, the roof sheet or alternately a sidewall may have a throughput 6 for the thermometer measuring the temperature inside the box and possibly another throughput or other fastening structure for installing the thermometer measuring the temperature outside the box. One or more growth prediction box is placed on the plantation immediately after the establishment of the plant stand (after the planting of the seed or immediately upon the planting of seedlings). One or more area corresponding to the average conditions in the cultivation is selected for the location. The plants growing in the growth prediction box may be watered at times if it is desirable to create conditions in which water will not be a growth-limiting factor. The average daily temperature is measured inside and outside the box in order to calculate the heat summations. The temperature data are collected either manually, or preferably automatically into a data collection unit by exploiting available technology (data loggers, radio transmitters, computers, solar cells, etc.), wherein the calculation of the actual heat summation as a cumulative sum between the planting day and the observation day is carried out to the extent that the average daily temperature exceeds +5 °C. In other words, if the average temperature of a 24- hour period is +15 °C, the heat summation for that day is +10 °C. The size of the growth prediction box can be selected freely, but preferably the surface area of its bottom is, for example, 1/5 m 2 , 1/4 m 2 or 1/2 m 2 , in which case the threshold for weed control, i.e. the total number of weed plants growing within one square meter, can be calculated by simple multiplication. The weed species can also be identified and their distribution within the area tested can be determined, which further increases precision in the selection of the herbicide (active agent) or possibly herbicide mixtures best suited for the species. Furthermore, the amount used/dose of the control substance per hectare can be made precise with respect to the quantity of the species present. When the weeds have reached the stage most advantageous in terms of control of the species appearing within the growth prediction box, the heat summation for the period measured inside the box is read. This critical heat summation value will be used as date for prognosticating when the best time in terms of control efficiency is reached in the growth conditions outside the box, the actual cultivating conditions, i.e. when the said critical heat summation is reached outside the box. Depending on the growing conditions, the plant growth prediction box allows from a few days up to a few weeks to specify the control and/or fertilization decision and steps. The device according to the invention thus improves the farmer's decision- making possibilities for anticipatory and more economical weed control, and also reduces the control substance loads of the field, since the control steps can be targeted at the stage of growth most sensitive in terms of the development of the weed, by using the active agent best in terms of control efficacy, and thus routine sprayings, so-called general control, can be avoided. Respectively, the prognostication of the amount and time of supplementary fertilization need becomes more precise and the use of nutrients is thereby improved. Example Comparative growing test Tarso winter wheat was planted in the autumn, and a growth prediction box according to the invention was installed in the field in the middle of April the following year, i.e. immediately at the beginning of the growing season. Spring fertilization was carried out on May 3 by surface application of 100 kg of nitrogen per hectare. In a measurement performed on May 14, the height of the plant stand of the winter wheat in the box was 26 cm, the plant stand was at the 1-node stage (BBCH growth stage 1). Outside the box the height of the plant stand was 15 cm, the plant stand was at the 4-leaf stage (BBCH growth stage 14). On the basis of soil samples taken on May 14, the growth prediction box contained soluble nitrogen in the tilling layer 93 mg per one liter of soil, whereas the corresponding amount outside the box was 54 mg per one liter of soil. In the growth prediction box, bedstraw grew as a weed; its growth stage was optimal in terms of weed control, and it had surpassed its control threshold (1 plant/m " ) on May 14. A corresponding situation was not yet observable outside the growth prediction box. On the basis of the measurement of the effective heat summation, the development of the plant stand in the growth prediction box was about two weeks ahead of the development of the plant stand outside the box. On this basis the correct time for bedstraw control is when the corresponding heat summation is reached in the field conditions. On coiTesponding bases it is possible to estimate the need for supplementary nitrogen fertilization. Literature references Grandzinski, M., Van Overstraeten, M., Schroder, D. and Finch, R. 1998. Using maps and local calculation methods for spatially variable fertilizer recommendations. Proceedings No 422 of the International Fertilizer Society. 20 p. Pulkkinen, J. 1999. Kesalannoitus avomaalla. Leipa, No 5/1999, pp. 41-42. Scaife, A. & Stevens, K.L. 1984. Monitoring sap nitrate in vegetable crops: Comprison of test strips with electrode methods and affects of time of day and leaf position. Commun. Soil Sci. Plant Anal. 14: 761-771. Watanabe, S., Hatanaka, Y. & Inada, K. 1980. Development of a digital chloro- phyllometer; I. Structure and performance. Jpn. J. Crop Sci. 49: 89-90. Wollring, J., Reusch, S. & Karlsson, C. 1998. Variable rate nitrogen application based on crop sensing. Proceedings No 423 of the International Fertilizer Society. 28 p.

Claims: Claims 1. A growth prediction device for prognosticating the need for weed control and/or the need for supplementary fertilization, characterized in that it comprises a growth prediction box of a cover material permeable to light, the bottom (4) of the box being open, and the box comprising a roof (1) and a wall or walls (2, 3) and being provided with ventilation apertures (5). 2. The growth prediction device according to Claim 1, characterized in that it additionally comprises a thermometer measuring the temperature inside the box and measuring the temperature outside the box, and possibly a sensor measuring relative humidity and/or some other sensor. 3. The growth prediction device according to Claim 1 or 2, characterized in that the structure of the box has a throughput (6) or other fastening means for fastening the thermometer measuring the temperature inside the box and measuring the temperature outside the box, and possibly a sensor measuring relative humidity and/or some other sensor. 4. The growth prediction device according to Claim 2 or 3, characterized in that the thermometer and possibly the sensor measuring relative humidity and/or other sensor constitute part of an automatic data collection unit. 5. A method for monitoring the growth and development of weeds and for prognosticating a correctly timed, both qualitatively and quantitatively optimal use of active agents in terms of weed control, characterized in that a) there is installed in the plantation a growth prediction box of a cover material permeable to light, the bottom (4) of the box being open, and the box comprising a roof (1) and a wall or walls (2, 3) and being provided with ventilation apertures (5), b) the temperature inside the box and the temperature outside the box are measured daily, and the 24-hour heat summation is determined, c) the critical heat summation in the growth prediction box is determined for the time at which the weeds have reached a stage of growth advantageous in terms of weed control, d) the active agent and amount of the control substance are optimized on the basis of the weed data from the growth prediction box, e) the time at which the critical temperature is reached outside the box is determined and a control spraying is performed. 6. A method for monitoring the growth and development of cultivated plants in order to prognosticate the need for both qualitatively and quantitatively optimal supplementary fertilization at the correct time, characterized in that a) there is installed in the plantation a growth prediction box of a cover material peraieable to light, the bottom (4) of the box being open, and the box comprising a roof (1) and a wall or walls (2, 3) and being provided with ventilation apertures (5), b) the temperature is measured daily inside and outside the growth prediction box, and the 24-hour heat summation is determined, c) the critical heat summation at the stage of growth advantageous for supplementary fertilization in the growth prediction box is determined, and soil and/or plant samples are taken from the growth prediction box and from outside it, d) the results are compared on the basis of the analysis results and the heat summation differences in the growth prediction box and outside the box, and a decision is made regarding the need for supplementary fertilization, its amount, and its time.

Inventors: PELTONEN JARI, PELTONEN, JARI
Applicants: KEMIRA AGRO OY, PELTONEN JARI, PELTONEN, JARI
Application year: 2001
Main classification: A01G1
IPC codes: A01G9