N-Expert - A Decision Support System for Vegetable Fertilization in the Field

Fink, M.; Scharpf, Hans C.

doi:10.17660/actahortic.1993.339.6

Cited by 36 publications

(22 citation statements)

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“…WELL-N ) and N-Expert (Fink and Scharpf 1993), can be used for N recommendations. Simulation models can be used alone or together with soil and plant analysis which can check and guide the modelling simulations.…”

Section: Fertilizer Recommendationsmentioning

confidence: 99%

Effects of band placement and nitrogen rate on dry matter accumulation, yield and nitrogen uptake of cabbage, carrot and onion

Salo¹

1999

AFSci

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Adequate nitrogen (N) nutrition is essential for producing high vegetable yields of good quality. Fertilizer N not taken up by the plants is, however, economically wasteful and can be lost to the environment. Therefore the efficient use of N fertilizer, involving accurate estimation of crop N demand, choice of application method and timing of N fertilization, is an important research area. The effects of band placement and rate of N fertilization on inorganic N in the soil and the dry matter accumulation, yield and N uptake of cabbage, carrot and onion were studied in a three-year field experiment between 1993 and 1995. The plants were sampled during the growing season to determine the dry matter accumulation and plant N concentration. The inorganic N in the soil was determined during the growing period and after harvest. The N uptake was 3.8 kg, 1.6 kg and 2.5 kg per ton of edible yield of cabbage, carrot and onion, respectively. At the highest yield levels the N uptake including crop residues was 300 kg ha-1, 150 kg ha-1 and 120 kg ha-1 in cabbage, carrot and onion, respectively. In cabbage, almost 50% of N was in crop residues, whereas in carrot and onion only about 30% of N was in crop residues. Nitrogen uptake from non-fertilized soil varied from 29 to 160 kg ha-1, depending on the growing season and the crop. Cabbage and carrot utilised soil N efficiently, usually taking up more than 100 kg ha-1 from non-fertilized soil. Onion, on the contrary, utilised soil N relatively poorly, usually less than 50 kg ha-1 from non-fertilized soil. The rate of N uptake was low with all crops in early summer. After one month, N uptake increased in cabbage and onion. This uptake continued until harvest, i.e. mid-August for onion and early September for cabbage. Nitrogen uptake by carrot started rapidly only two months after sowing and continued until harvest at the end of September. High N rates often resulted in high N concentrations and N uptakes, but growth was not necessarily increased. One month after fertilization, most of the N placed was still near the original fertilizer band and at the depth of 5-10 cm. At that time, broadcast N was at a depth of 0-5 cm. After harvest the soil mineral N content was generally low, i.e. below 25 kg ha-1 at the depth of 0-60 cm. Onion was an exception with poor growth in 1994, when soil mineral N after the highest N rate was 80 kg ha-1 at a depth of 0-60 cm after harvest. The placement distance in the cabbage experiment, 7.5 cm in the side and 7 cm below cabbage transplants, resulted in lower plant growth and N uptake than broadcasting of N at the beginning of the growing periods 1993 and 1994. Towards harvest differences between application methods decreased, although in 1993, placement of N still led to 6% lower cabbage yields than broadcasting of N. In 1993, high N rates increased cabbage dry weight and N uptake towards harvest, and this effect was more pronounced when N was broadcast. In 1994, soil N mineralisation was high, and only non-fertilized cabbages took up less N than fertilized plants. Carrot was remarkably insensitive to N fertilization. Carrot yields were similar with and without N fertilizers. Band placement and N rate did not affect carrot growth and N uptake. In 1993, band placement and high rates of N increased onion growth and bulb yield more than broadcasting. In 1994, onion growth was poor and treatments did not affect plant N concentrations or growth. Apparent recovery of fertilizer N was increased in 1993 by low N rates or band placement. This result that band placement of N does not much affect vegetable growth is in agreement with most previous studies. With onion, probably due to the sparse root system, positive effects of N placement are most likely to be found.;

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Section: Fertilizer Recommendationsmentioning

confidence: 99%

Effects of band placement and nitrogen rate on dry matter accumulation, yield and nitrogen uptake of cabbage, carrot and onion

Salo¹

1999

AFSci

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“…Several N recommendation systems for controlling N fertilization in open-field vegetable production, are carried out in some intensive vegetable crop production regions in Europe and North America, such as N min method (Wehrmann and Scharpf 1986), KNS system (Lorenz et al 1989), N-Expert system (Fink and Scharpf 1993), and pre-sidedress soil nitrate testing (PSNT) technique (Hartz et al 2000). To ensure cropspecific N demand, considering crop N uptake, soil N min buffer and inevitable N loss (including leaching, denitrification, NH 3 volatilization, etc.…”

Section: Introductionmentioning

confidence: 99%

Yield and Nitrogen Balance of Greenhouse Tomato (Lycopersicum esculentum Mill.) with Conventional and Site-specific Nitrogen Management in Northern China

Chen

Jiang

et al. 2006

Nutr Cycl Agroecosyst

134

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In a greenhouse experiment with tomato, the N fertilizer reduction potential, tomato yield, N use and environmental implications were examined, in a comparison of site-specific N management with conventional N fertilization during three successive growing seasons from Feb. 2004 to Jun. 2005 in Shouguang, a typical greenhouse vegetable production region in Shandong province, Northern China. Fertilizer N recommendation with site-specific management was based on the difference between N target value and soil initial nitrate-N content (0-0.3 m) with pre-sidedress soil nitrate testing (PSNT) and nitrate-N applied from irrigated water. The same basal dressing of 8, 11 and 8 t ha À1 of chicken manure (supplying 260, 360 and 316 kg N ha À1 in the first, second, and the third growing season, respectively) was broadcasted with conventional N, site-specific N and N from manure three treatments. The N target value with site-specific management was 300 kg N ha À1 in the first season, and then modified to 200 kg N ha À1 in the second and third seasons. In comparison with the fertilizer N applied rate with conventional N management (870, 720 and 630 kg N ha À1 in the three seasons, respectively), site-specific management reduced N fertilizer by 62, 78 and 80% without significant influences on tomato yield. The fruit yield of tomato with only basal dressing manure treatment was significantly decreased in the second season, compared with conventional N management. The nitrate content in 0-0.9 m soil depth with site-specific management was much lower than that with conventional N management in all three seasons. The 53-83% of emitted nitrous oxide (N 2 O) was measured from transplanting to the first sidedressing in the three seasons, strongly related to dryingwetting soil process. As a result, the cumulative emission with site-specific management was only reduced by 38% than that with conventional N management throughout three seasons. Considering N release from mineralization and irrigation water, site-specific N management could efficiently control N application in intensive irrigated-vegetable production region. Thus, it is valuable to obtaining vegetable crops with high yield and economic return while alleviating the risk of environmental pollution. But it is necessary to optimize irrigation regime to minimize N loss through nitrate leaching and N 2 O emission.

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“…The N fertilizer recommendations were determined by a calculation procedure based on the N-Expert system of Fink and Scharpf (1993) with three Table 1 Growing periods and basal dressings of organic manure and inorganic P Here, soil N min safety margin refers to the critical residual soil N min in the root zone required to maintain crop growth.…”

Section: Methodsmentioning

confidence: 99%

“…Appropriate nitrogen fertilizer recommendation systems depend on the type of crop and, in most cases, the amount of mineral N available in the root zone at the beginning of the growing season. The KNS-system (Kulturbegleitende N min Sollwerte) and the N-Expert system have been applied for sustainable open-field vegetable production in Europe for many years (Lorenz et al, 1989;Fink and Scharpf, 1993). The KNS system takes into account the N requirement of the crop and the soil N supply during the remaining growth period by using tables with empirical data and by measuring soil mineral N. Its N fertilizer recommendations are derived from calculation of three output components (N uptake, N loss and immobilization, and the N min safety margin) and three input components (N release from soil organic matter, N release from crop residues, and residual N min ).…”

Section: Introductionmentioning

confidence: 99%

“…The KNS system takes into account the N requirement of the crop and the soil N supply during the remaining growth period by using tables with empirical data and by measuring soil mineral N. Its N fertilizer recommendations are derived from calculation of three output components (N uptake, N loss and immobilization, and the N min safety margin) and three input components (N release from soil organic matter, N release from crop residues, and residual N min ). However, the N uptake pattern is the core of the recommendation system (Fink and Scharpf, 1993).…”

Section: Introductionmentioning

confidence: 99%

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Use of a Modified N-Expert System for Vegetable Production in the Beijing Region

Chen¹,

Zhang²,

Li³

et al. 2005

Journal of Plant Nutrition

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A series of field experiments were conducted over a three-year period to test a modified N-Expert system (the decision support system for nitrogen recommendations) with different irrigation regimes for a rotation of amaranth (Amaranthus tricolor L.), spinach (Spinacia oleracea L.), and cauliflower (Brassica oleracea L.). Local commercial fertilizer practice based on farmer surveys was selected as the control, and irrigation treatments followed conventional practice with a balanced irrigation schedule. Some parameters, notably target yields and net mineralization rates, were modified according to local conditions, and most were referenced from the database of the N-Expert system in the first cultivation year of the rotation. Parameters were tested in earlier field experiments and were fine-tuned in later experiments. No significant yield reduction occurred below conventional nitrogen (N) practice using the recommended N treatment (N2) with different water treatments, except for irrigation treatments between 60% and 90% of PESW (plant extractable soil water: the difference between field capacity and wilting point) in 2000 and conventional irrigation practice in 2001 for cauliflower. There was a significant decrease in residual N min at harvest in treatments using the modified N-Expert recommendation system compared with conventional N practice. This indicates that there is considerable potential for use of the N recommendation system for sustainable vegetable production in the North China Plain.

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N-Expert - A Decision Support System for Vegetable Fertilization in the Field

Abstract: The computer program N-Expert calculates field specific fertilizer recommendations for vegetable crops. Since the calculation is based on simple plant growth-and soil-models, which need only few input data, the program can be used by both growers and advisers.

Cited by 36 publications

References 1 publication

Effects of band placement and nitrogen rate on dry matter accumulation, yield and nitrogen uptake of cabbage, carrot and onion

Effects of band placement and nitrogen rate on dry matter accumulation, yield and nitrogen uptake of cabbage, carrot and onion

Yield and Nitrogen Balance of Greenhouse Tomato (Lycopersicum esculentum Mill.) with Conventional and Site-specific Nitrogen Management in Northern China

Use of a Modified N-Expert System for Vegetable Production in the Beijing Region

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