Method and system for providing plants with water comprising a high nitrate content

Abstract

The present invention relates to a method for producing water having a stable high nitrate content, an organic fertilizer comprising the water having a stable high nitrate content thus produced, and use of the water having a stable high nitrate content in a method for the organic cultivating of a plant in a substrate. The present invention further relates to a continuous flow system for supplying plants with the water having a stable high nitrate content.

Claims

1. A method for producing water having a stable nitrate content of between 10-200 mmol/l in a continuous flow system, the method comprising: a) contacting water comprising organic matter having at least 100 ppm of nitrogen compounds with ammonification and nitrifying bacteria to obtain water having a nitrate content of between 10-200 mmol/l; b) passing the water obtained in step a) through a membrane to separate organic matter, fungi, and/or bacteria from the water, wherein the membrane has a pore size of between 0.01-0.1 m; and c) optionally collecting the water, which has a stable nitrate content of between 10-200 mmol/l and which is substantially free of organic matter, fungi, and/or bacteria, wherein no extra mineral salt is added to the water, wherein the stable nitrate content is the result of the step of passing the water through the membrane, and wherein the nitrate content of the water is stable for at least one week, and wherein the continuous flow system comprises a bioreactor in which both ammonification and nitrifying bacteria are employed and wherein the bioreactor comprises the membrane to separate organic matter, fungi, and/or bacteria from the water.

2. The method as claimed in claim 1, wherein step a) is performed at a pH of between 5.0-9.0.

3. The method as claimed in claim 1, wherein the membrane has a pore size of 0.04 m.

4. The method as claimed in claim 1, wherein the water comprising organic matter is in the bioreactor for a minimum of 24 hours.

5. The method as claimed in claim 1, wherein the water comprising organic matter is in the bioreactor between 24 and 48 hours.

Description

FIGURES

(1) FIG. 1 is a schematic overview of one embodiment of the continuous flow system of the present invention. In this one, non-limiting, example, organic matter in the form of HOB, together with micronutrients, calcium and water, are added to a bioreactor where nitrification takes place. The bioreactor is in connection with a membrane tank in which the water from the bioreactor is passed through a membrane. Water from the membrane tank can flow back to the bioreactor or is transferred to a day storage tank. Water from the day storage tank is transferred to the greenhouse.

(2) FIG. 2 is a graph that shows the yield of sweet bell pepper plants after irrigation with water produced according to the method of the present invention. After 44 weeks of cultivation, the yield was about 32 kg/m.sup.2.

(3) FIG. 3 is a graph that shows the yield of tomato plants after irrigation with water produced according to the method of the present invention. After 44 weeks of cultivation, the yield was about 59 kg/m.sup.2.

EXAMPLES

Example 1The Nitrate Content Remains Stable After 1 Week of Storage

(4) Irrigation water for growing sweet bell pepper plants and tomato plants was produced in a bioreactor designed and developed by the present inventors. This bioreactor provides a continuous flow system for producing water with a stable high nitrate content. It comprises three tanks: one tank into which an organic fertilizer mixture is provided, one tank in which the organic nitrogen from proteins in the organic fertilizer mixture is converted into NO.sub.3.sup. nitrogen (nitrate), and one tank in which the mixture is passed through a membrane. The resulting water has a high nitrate content and is substantially free of organic matter, fungi and bacteria. It also does not contain calcium nitrate, potassium nitrate, magnesium nitrate, ammonium nitrate, or potassium phosphate.

(5) In a first step, 6 liters per m.sup.3 water comprising about 297 ppm nitrogen was provided in the first tank. This solution was transferred to a second tank comprising ammonification and nitrifying bacteria. The second tank is in connection with a third tank comprising a 0.04 m membrane. After a minimum residence time of 24 hours, the mixture in the second tank is transferred to the third tank, where it is passed though the membrane. The resulting water was collected and a sample thereof directly analyzed. Another sample in which the nitrate content was measured was taken after 1 week of storage. The results are presented in Table 1.

(6) TABLE-US-00001 TABLE 1 Analysis of composition of water produced via continuous flow system (directly after collection of water from tank 3 and after 1 week of storage. Converted results: ppm = mg/l and ppb = g/l. Water directly Water after 1 week after process of storage pH 7.4 7.2 EC 2.0 2.1 mS/cm 25 C. Cations: mmol/l ppm mmol/l ppm NH.sub.4 1.6 29 2.0 36 K 4.9 192 5.0 196 Na 1.1 25 1.2 28 Ca 4.4 176 4.1 164 Mg 1.1 27 1.1 27 Anions: mmol/l ppm mmol/l ppm NO.sub.3 12.0 744 10.8 670 Cl 1.0 35 0.9 32 S 1.2 38 1.1 35 HCO.sub.3 2.0 122 3.6 220 P 0.67 21 0.68 21 Micronutrients: mol/l ppb mol/l ppb Fe 27 1508 22 1229 Mn 12 659 11 604 Zn 3.5 229 305 229 B 75 811 72 778 Cu 0.6 38 0.6 38 Mo 1.4 134 1.4 134 Si (mmol/l; <0.01 <0.3 <0.01 <0.3 ppm)

Example 2Use of the Water Comprising Stable High Nitrate Content for Growing Pepper and Tomato Plants

(7) The collected water from Example 1 was enriched with micronutrients as desired, as well as extra magnesium sulfate or potassium sulfate. These are minerals from earth and allowed in organic cultivation. After adding nutrients, the water was diluted to the demanded conductivity specific to the crop, which is 2.6 mS/cm for pepper and 3 mS/cm for tomato. It was subsequently transported through an irrigation system to the greenhouse where sweet bell pepper plants of the orange pepper variety Orbit and tomato plants of the variety Completo grafted onto an estamino understem were grown in coco substrates under normal growing conditions. The sweet bell pepper plants were grown in a density of 2.2 plants/m.sup.2, the tomato plants in a density of 1.45 plants/m.sup.2. The plants were irrigated as usual. A sample of the irrigation water was taken and analyzed. The results are presented in Table 2.

(8) The yield of sweet bell pepper plants is shown in FIG. 2.

(9) The yield of tomato plants is shown in FIG. 3.

(10) These yields are comparable to conventional growing with mineral fertilizers, and are clearly increased with respect to the yields obtained by irrigating the plants with water that has not been passed through a membrane.

(11) TABLE-US-00002 TABLE 2 Analysis of composition of water produced via continuous flow system. (1) sample taken directly after collection of water from tank 3. (2) sample taken from irrigation water. Converted results: ppm = mg/l and ppb = g/l. Water Water Water directly used for used for after irrigation of irrigation of process weet bell tomato (1) pepper (2) (2) pH 6.2 6.1 6.3 EC mS/cm 25 C. 3.2 2.8 3.1 Cations: mmol/l ppm mmol/l ppm mmol/l ppm NH.sub.4 0.5 9.0 0.2 3.6 0.1 1.8 K 7.2 282 6.6 258 9.8 383 Na 2.2 51 2.4 55 2.4 55 Ca 7.6 305 7.2 289 6.7 269 Mg 2.4 58 3.2 78 3.8 92 Anions: mmol/l ppm mmol/l ppm mmol/l ppm NO.sub.3 21.9 1358 17.6 1091 16.7 1035 Cl 2.1 74 1.8 64 1.9 67 S 2.7 87 4.3 138 6.8 218 HCO.sub.3 <0.1 <6.2 <0.1 <6.2 <0.1 <6.2 P 1.31 41 0.70 22 0.68 21 Micronutrients: mol/l ppb mol/l ppb mol/l ppb Fe 60 3351 142 7930 126 7037 Mn 20 1099 33 1813 25 1373 Zn 12 784 15 981 15 981 B 96 1038 107 1157 105 1135 Cu 0.9 57 1.3 83 1.0 64 Mo 1.1 106 1.6 154 1.2 115 Si (mmol/l; ppm) 0.03 0.8 <0.01 <0.3 <0.01 <0.3