Current N recommendation schemes are based on the Maximum Economic Yield (MEY), as obtained at “economic optimum’ fertilizer application rates. Environmental standards for the amount of mineral N left in the soil at harvest time will soon restrict fertilizer rates to obtain an Environmentally Acceptable Production (EAP). For MEY, but especially for EAP, spatial variability of N supply in a field which is managed as if it were a homogeneous unit should be taken into account. Degree of spatial variability in N supply should be explicitly taken into account in future discussions of the conflict between environmental and production targets.
Tag: minerals
Modelling root architecture and phosphorus uptake in agroforestry
A modified version of the WaNuLCAS model [Water, Nutrient and Light Capture in Agroforestry Systems, which models water, nitrogen and light interactions in agroforestry systems] is outlined. The modified model includes phosphorus as a second nutrient, with a range of phosphorus (P) acquisition mechanisms for crops and trees, and interactions via recycling and rhizosphere modification
Phosphorus uptake and maize response to organic and inorganic fertilizer inputs in Rubona, Southern Province of Rwanda
Green manure of multipurpose trees is known to be a good source of nutrients to cropHowever, most agroforestry species do not have adequate phosphorus (P) in their leaves. Supplementing green manure with moderate dose of P is a beneficial strategy to improve food security in Rwanda. This study examines the effects of Calliandra calothyrsus Meissner, Tithonia diversifolia Hensley A.Gray and Tephrosia vogelii Hook.f. green manure applied independently or in combination with triple super phosphate (TSP) and lime on maize yield and P uptake in the Oxic Tropudalf of Rubona, Rwanda. The treatmentswere the control, lime at 2.5 t ha-1,TSP at 25 and 50 kg P ha-1, leafofC. calothyrsus, T. diversifolia, and T. vogelii each at 25 and 50 kg P ha-1, respectively. Leaf shrubs biomass,TSPand limewere applied for four consecutive seasons (2001-2004). The results showed that the combination of greenmanure with TSP at a rate of 50 kg P ha-1 significantly increased maize yield from 24 to 508% when compared to the control and T. divesifolia combined with TSP was leading (508%). Equally, the same treatments as indicated above showed higher P uptake (15.6-18. 6 kg P ha-1) than the control (5 kg P ha-1) and 65% of maize yields variation was explained by total P uptake. The plant residues quality such as C:N ratio, total plant N, and P significantly Calliandra calothyrsusinfluenced the variability of maize grain yields.
Evolution of nutrients in some leafy vegetables growth
In Côte d’Ivoire several leafy vegetables are grown and consumed. However, their maturity stages for consumption are not really defined. So, six leafy vegetables (lagos spinach, jute mallow, roselle, spinach, black nightshade and amaranth) were grown during 2 months at the Agronomic Research Station of Anguededou (Abidjan). They were analysed each weeks for pH, proteins, sugars, fibers, vitamin C, ß-carotene, minerals and oxalic acid content. The results revealed that roselle was the most acid leafy vegetable and had the highest oxalic acid content. Protein level decreased during leafy vegetables growth. Total sugars level was constant between the 2nd and 5th weeks. Lagos spinach had the most elevated fibers content at the 3rd week (37.17% for soluble fiber and 66.1% for insoluble fiber). Amaranth and black nightshade had the highest vitamin C content at 7th week (64.44 and 66.67 mg/100 g fresh weight (FW) respectively). Moreover, roselle had the highest ß-carotene content (64.12 mg/100 g FW, at the 5th week). Phosphorus content of amaranth and black nightshade was the highest at 6th week with respectively 0.45 mg/100 g dry matter (DM) and 0.33 mg/100 g DM. Magnesium level was constant during leafy vegetables growth. Spinach and jute mallow had the highest iron content at the 5th week (70 and 88.8 mg/100 g DM). The most elevated calcium level was found in spinach (3.68 g/100 g DM at the 6th week) and in lagos spinach (4.8 g/100 g DM at the 8th week). On the other hand, the lowest potassium content was in roselle (1.84 g/100 g DM at the 8th week). The propitious period for leafy vegetables consumption is between the 3rd and the 5th weeks of growth because nutrients levels are maximal.
Alley cropping of maize with calliandra and leucaena in the subhumid highlands of Kenya: Part 2. Biomass decomposition, N mineralization, and N uptake by maize
A major challenge in developing agroforestry approaches that utilize tree-leaf biomass for provision of N to crops is to ensure synchrony between the N released from decomposing prunings and N demand by crops. A study was conducted in the subhumid highlands of Kenya to assess the rate of decomposition and mineralization of soil-incorporated Calliandra calothyrsus Meissner (calliandra) and Leucaena leucocephala (Lam.) de Wit (leucaena) tree biomass and maize roots (Zea mays L.) both in an alley cropping and a sole cropping system. The amount of mineralized N peaked four weeks after planting (WAP) maize in all the treatments during both seasons of 1995. Cumulative mineralized N at week 20 ranged from 114 to 364 kg N ha1 season1, the absolute control treatment giving the lowest and the prunings-incorporated treatments giving the highest amounts in the two seasons. Total N uptake by maize, ranging from 42 to 157 kg ha1 season1, was lowest in the ‘alley-cropped, prunings-removed’ treatments, and highest in the ‘non alley-cropped-prunings-incorporated’ treatments. The apparent N recovery rate by maize was highest in the fertilizer applied treatments in the two seasons. Decomposition rate constants (kD) ranged from 0.07 to 0.21 week1, and the rates among the different plant residues were as follows: leucaena < calliandra < maize roots. Nitrogen release rate constants (kN), ranging from 0.04 to 0.25 week1, followed a similar pattern as the rate of decomposition with leucaena releasing the highest amount of N followed by calliandra and lastly by maize roots
Waste recovered by-products can increase growth of grass-clover mixtures in low fertility soils and alter botanical and mineral nutrient composition
The effectiveness of four by-products (biogas digestate, pot ale, rockdust and wood ash) as fertilisers of a perennial ryegrass (Lolium perenne)–red clover (Trifolium pratense) mixture in terms of biomass production, botanical composition and macro- and micronutrient concentrations was tested in an outdoor pot trial. This was carried out over two growing seasons using two inherently low-fertility soils used for forage production. Macro- and micronutrients (N, P, K, Ca, Mg, Co, Cu, Mn, Mo and Zn) relevant for crops and livestock were determined in soils and plants. All the by-products increased overall biomass production and affected nutrient concentrations of the individual plant species to varying degrees. In addition the competitive balance between grass and clover was altered leading to different botanical composition in the different treatments and consequently differences in the nutrient concentrations of the species mixture. Changes were due to the nutrients applied in the by-products per se and/or to changes in the soil chemistry caused by the by-products. The results suggest a potential to enhance agricultural productivity through improved production and quality of forage on less fertile land by matching of by-products and soil properties.
Plant seeds as source of nutrients and phytochemicals for the Indian population
Plant seeds are major sources of nutrients and bioactive compounds for human beings and vary across different locations. In addition, they are under used foods that could be a good complement for the daily nutrition of people. Therefore, the aim of this study was the analysis of different physical parameters, nutrients and bioactive compounds of 60 plant seeds belonging to 48 species and 9 families. The seeds were collected in 2016–2017 in the Raipur area, India (21.25°N 81.63°E), from three different locations. Fat, protein, starch, total polyphenols and mineral contents ranged from 0.7 to 44.2, 1.6 to 68.5, 11.3 to 84.0, 0.01 to 3.85 and 0.67 to 4.91 g/100 g (dry weight) respectively. Regarding physical properties, the heavier seeds were covered with thick testa over the range of 3.0 to 40% of the seed mass. Higher moisture and ash fractions for the starchy (cereal and pulses) and weed seeds were also found. The most abundant mineral elements in the seeds were P, S, K, Mg, Ca, Fe and Zn. Finally, it was calculated the contribution of the consumption of seeds to the daily macronutrients and micronutrients intake for Indian population, reaching up to 38, 13 and 25% for proteins, fat and carbohydrates respectively. © 2021 The Authors. International Journal of Food Science & Technology published by John Wiley & Sons Ltd on behalf of Institute of Food, Science and Technology (IFSTTF)