Fertigation

Los actuales sistemas intensivos de producción agraria, usan técnicas de riego localizado y el modo
peculiar de cultivar en un medio más o menos artificial: suelo natural modificado, suelo artificial,
sustrato e incluso cultivo en una solución salina. Estas técnicas alteran las funciones tradicionales
del suelo, como reserva de agua y nutrientes, sirviendo, fundamentalmente, en estos casos como
soporte del cultivo. Las nuevas tecnologías intentan ofrecer el agua y los nutrientes, en un medio
subsaturado, lo más directamente posible a las plantas, tratando de minimizar las pérdidas por
evaporación y lixiviación.
La actividad agraria, en la actualidad, genera demasiados residuos e impactos ambientales,
comprometiendo el futuro de muchas áreas geográficas por problemas de contaminación fuentes de
agua y de suelos debido al uso sin control de agroquímicos. Ante esta situación la ley de mínimos,
que rige en agronomía el estudio de nutrición de los cultivos, debe completarse con una ley de
máximos que evite el despilfarro de agua, de fertilizantes y la problemática ambiental resultante de
su lixiviación.

This paper focuses on modeling and identification of environmental climates inside naturally ventilated tropical greenhouse (NVTG). The NVTG climate model is an essential tool for developing the climate control system. A real-time wireless monitoring system for measuring prototyped NVTG environmental climates for chili plantation was developed. The variables to estimate the NVTG outputs variables namely internal relative humidity and internal temperature are external temperature, external humidity, irradiance, and wind speed. Modeling based on mathematical equation as well as using system identification (SI) technique is outlined. The paper also highlights on SI procedure namely data acquisition, identified model structure that represents NVTG using NARX and ARX model structures, parameter estimation technique, and model validation. Simulation studies reveal that linear and nonlinear polynomial models are able to model and simulate the NVTG performance.

Nutrient Use Efficiency of Anthurium andreanum ‘Pink Fever’, Grown on Vertical Gardens Trough Fertigation (automatic drip irrigation)
Abstract
Vertical gardens are modern type of  oral arrangements that are becoming widely used in the interior. As a part of aesthetics, vertical panels of plants should be with optimal ornamental performance. The great diversity of used plants of different species does not permit application of differential feeding that satis es the nutrient needs of each plant type.
The purpose of the present study is to establish the nutrient use ef ciency of Anthurium andreanum Linden ‘Pink Fever’, grown in a vertical garden together with other foliage ornamentals with different nutrition needs. The experimental plants are of Dutch origin. Part of them is grown as control-plants without external source of nutri- ents. Several plants are planted in the vertical garden with roots mixed with peat substrate in pockets of geotextile on panel size 70/160 cm with automatic drip irrigation system performing with 500 ml water/2 times/24 h. Suspen- sion fertiliser Lactofol (500 ml, 1% solutiоn) was applied once a week containing nitrogen – 6.0%, phosphorus (P2O5 ) – 4%, potassium (K2O) – 4%; boron 0.3% and trace elements: copper, manganese , molybdenum, zinc and physiologically active and other substances. The vertical garden is grown at controlled light intensity, humidi- ty and temperature for 15 months. In Central University Laboratory “Ecology and Environmental Protection” are analyzed nutrient values and other parameters (pH, macronutrients, conductivity and salt content) before and af- ter the experiment in: peat substrate, leaf samples, solution of fertiliser accordingly and in the lysimetrical waters (after soaking and draining from the geotextile). Certain ef ciency of the applied fertigation nutrition is proved – no de ciency of essential nutrients and absence of de ciency symptoms within the study period, absence of salinity or signi cant loss of salts in lysimetrical water.

Water and nitrogen (N) are two key limiting factors in orange (Citrus sinensis) production. The amount and the timing of water and N application are critical, but optimal strategies have not yet been well established. This study presents an analysis of 47 fertigation strategies examined by a coupled soil-crop model. The strategies include 27 main scenarios with a factorial design of 3 irrigation levels (420, 520 and 640 mm, representing 80%, 100% and 120% of water demand), 3 N input levels (100, 200 and 300 kg ha-1) and 3 main N split applications, and 20 additional scenarios testing alternative N split applications, extreme rainfall years (dry and wet) and different soil textures.
The simulations showed that orange yields were strongly influenced by N input and N split applications, but not so much by irrigation. Increasing water and N input led to increased N losses (via leaching and denitrification), and there were significant positive interactions between water and N input with respect to N losses. On average, low N input (100 kg ha-1) led to relatively low N losses (16 kg ha-1) but resulted in low yield (33 ton ha-1, 25% yield reduction). High N input (300 kg ha-1) produced a high yield (43 ton ha-1) but led to large N losses (104 kg ha-1). Optimal N input (200 kg ha-1) significantly reduced N losses (45 kg ha 1) without yield reduction. Importantly, with optimal N input, improving N split applications significantly increased yield by 13% and reduced N losses by 40%, compared to sub-optimal N splits.
Significant interactions between water inputs, N inputs and N split applications in yield and N losses indicate that the optimization of fertigation strategies must consider these three key variables simultaneously. Our results clearly show that over-optimal water and N inputs lead to large water and N losses. Reduced irrigation (80% of water demand) and N input equal to N demand (200 kg ha-1) can significantly reduce N losses without yield reduction. The N split applications should be adjusted to the N demand of the crop during the growing season. Our study focused on a Mediterranean climate, but the methodology and results can be applied to other situations in the world.

Water and nitrogen (N) are two key limiting factors for citrus production. Reported effects of water and N inputs on citrus yield, water use efficiency (WUE) and N use efficiency (NUE) vary greatly, mainly due to differences in cultivars, tree age, climate, soil types, and water and N input levels. So far, no systematic analysis has been performed, and as a result, the interactive effects of water and N inputs on yield, WUE and NUE of citrus orchards are unknown. Also, gaps between attainable and actual yields, WUE and NUE have not been established yet. Here, we report on a global meta-analysis of yields, WUE and NUE of citrus production systems, using 1009 observations from 55 studies, conducted in 11 countries. Median citrus yields ranged from 30 to 60 t ha-1, which were in between average global yields (range 10-30 t ha-1) and attainable yields (range 60-90 t ha-1). Median WUE ranged from 2.5 to 5 kg m-3 and median NUE from 150 to 350 kg kg-1. Citrus yields were related to water and N inputs and tree age. Relationships between water and N inputs and yield, WUE and NUE were also analysed for sub-datasets and quantiles, to examine the relationships near the extremes. There were statistical significant interactions between water and N inputs in yield and NUE, but not in WUE. This indicates that studies aiming at the optimization of water and N inputs must consider interactions and optimize water and N inputs simultaneously. Based on our analyses, we estimated that reducing over-optimal irrigation to optimal irrigation may increase citrus yield by 20%, WUE by 30% and NUE by 15%. Similarly, reducing over-optimal N fertilization to optimal N fertilization may increase yield by 10%, WUE by 15% and NUE by 40%. We concluded that there is room for a significant increase in yield, WUE and NUE through the simultaneous optimization of water and fertilizer N inputs via precision fertigation