scholarly journals Biochar Effects on Mineral Nitrogen Leaching, Moisture Content, and Evapotranspiration after 15N Urea Fertilization for Vegetable Crop

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 331 ◽  
Author(s):  
Rasheed Ahmed ◽  
Yuzhong Li ◽  
Lili Mao ◽  
Chunying Xu ◽  
Wei Lin ◽  
...  

Globally, mineral nitrogen (N) losses as nitrate leaching (NL) are a substantial portion of applied fertilizer and cause surface and sub-surface water contamination. To precisely measure NL and its interlink parameters, biochar soil amendment was tested in this study. Three treatments—biochar (BC), without biochar (WB) with 15N urea (300 kg/ha), and control (no fertilization)—were tested in soil-filled lysimeters (circular PVC (Polyvinyl Chloride) tank of 30 cm diameter and 35 cm height) equipped with moisture content sensors and weighing assembly for the consecutive two cropping of Brassica Camprestis Var. Chinensis. The 15N-urea in the first season and the poultry manure in the second season were applied, but the fate of the 15N was examined in leachate, dry matter, and soil. As compared to WB, BC significantly decreased mineral N leaching, including nitrate levels (35%), increased electrical conductivity (68.5%), and water availability (20% inches per foot), while there was a non-significant increase in biomass per plant (2.84%), evapotranspiration (8.33%), dry matter (6.89%), and a decrease in mean leachate volume (7.63%). Moreover, BC accumulated values were higher than WB, as N uptake (38%), water use efficiency (12.24%), maximum fresh weight (11.4%), and soil N retained (185%) after cropping. The soil pH, the bulk density, and the total nitrogen were changed but presented non-significant differences. Therefore, biochar can increase soil N retention and available water to improve water use efficiency and decrease potential N leaching.

2019 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Jinji Zhang ◽  
Zhuangzhuang Cao ◽  
Haibo Dai ◽  
Zhiping Zhang ◽  
Minmin Miao

Fertigation with surface drip has been introduced and broadly applied for vegetable cultivation in the Eastern China, which presents high precipitation and always has shallow groundwater. To estimate the influence of high groundwater level on the tomato nitrogen (N) and water use efficiency and develop new sensor-based fertigation technology, experiments were executed in plastic greenhouse in the experimental farm of Yangzhou University located in the suburban of Yangzhou city during 2016-2017 growing seasons using a block randomization with three replications. Three N dosages and 4 watering treatments were carried out in this experiment. The data indicated that irrigation threshold of -35 kPa was optimum to get the maximum production of tomato. In this treatment, the value of estimated plant evapotranspiration (ETc) was much higher than total applied water volume, suggesting high groundwater table had a significant contribution on the tomato ETc and a sensor-based irrigation strategy should be more accurate than the simulated ETc irrigation method to calculate the water demand under this condition. In addition, our results indicated that high groundwater level had a positive effect to alleviating N leaching. Finally, we can conclude that fertigation technology enhanced the N use efficiency (NUE) and water use efficiency (WUE) and three fourths of the calculated N dosage (according to a traditional nutrient equation) was sufficient to optimize tomato yield.


2002 ◽  
Vol 42 (7) ◽  
pp. 945 ◽  
Author(s):  
J. L. Jacobs ◽  
G. N. Ward ◽  
A. M. McDowell ◽  
G. Kearney

Effect of cultivation practice and sowing time on soil moisture retention at sowing, growth rates, dry matter yield, water use efficiency and nutritive characteristics (metabolisable energy, crude protein, neutral detergent fibre, water-soluble carbohydrates and starch) of turnip, pasja and rape was determined on 2 soil types (site A and B) over 2 years. Cultivation treatments were: optimum full inversion, an optimum non-inversion cultivation and over cultivated. At each site, cultivation treatments were imposed at 2 different times (early and late).Results showed few differences in soil moisture at sowing between the 3 cultivation systems. Where seedbeds were prepared earlier rather than later, soil moisture at sowing was higher. Given that there was relatively little difference in soil moisture between cultivation treatments within a sowing time, it is likely that rainfall events may have confounded cultivation effects.Apart from year 2 at site A, the water use efficiency of turnip was higher than for pasja and rape. It is proposed that the lower value in year 2 may be due to root development being retarded by low moisture availability, particularly at the later sowing date, thus leading to a lower dry matter yield.Despite no cultivation effects on soil moisture at sowing, there appeared to be clear advantages for the full inversion technique in terms of subsequent weed germination. Generally, weed numbers post germination were lower for this cultivation method compared with both non-inversion techniques. In conclusion, the cultivation techniques used had little effect on soil moisture at sowing and subsequent dry matter yields, provided the resultant seedbed was well-prepared, fine, firm and weed free. Full inversion cultivation techniques in areas where broad-leaved weeds are a problem may substantially reduce subsequent weed burdens. Early sowing where possible may reduce the likelihood of crop failure through the provision of adequate soil moisture at sowing and increase the incidence of rain during the growing period. Timing of sowing will vary according to paddock requirements during early spring (e.g. grazing or forage conservation), soil type, and trafficability for cultivation.


1997 ◽  
Vol 37 (6) ◽  
pp. 667 ◽  
Author(s):  
W. M. Strong ◽  
R. C. Dalal ◽  
J. E. Cooper ◽  
J. A. Doughton ◽  
E. J. Weston ◽  
...  

Summary. Continuous cereal cropping in southern Queensland and northern New South Wales has depleted native soil nitrogen fertility to a level where corrective strategies are required to sustain grain yields and high protein content. The objective of this study was to examine the performance of chickpea in chickpea–wheat rotations in terms of yields, water use and N2 fixation. The effects of sowing time and tillage practice have been studied. Chickpea grain yields varied from 356 kg/ha in 1995 to 2361 kg/ha in 1988; these were significantly correlated with the total rainfall received during the preceding fallow period and crop growth. Almost 48% of total plant production and 30% of total plant nitrogen were below-ground as root biomass. Mean values of water-use efficiency for grain, above-ground dry matter, and total dry matter were 5.9, 14.2 and 29.2 kg/ha.mm, respectively. The water-use efficiency for grain was positively correlated with the total rainfall for the preceding fallow and crop growth period although cultural practices modified water-use efficiency. The potential N2 fixation was estimated to be 0.6 kg nitrogen/ha.mm from 1992 total dry matter nitrogen yields assuming all of the nitrogen contained in chickpea was derived from the atmosphere. Sowing time had a much larger effect on grain yield and N2 fixation by chickpea than tillage practice (conventional tillage and zero tillage) although zero tillage generally increased grain yields. The late May–early June sowing time was found to be the best for chickpea grain yield and N2 fixation since it optimised solar energy use and water use, and minimised frost damage. Nitrogen fixation by chickpea was low, less than 40% nitrogen was derived from atmosphere, representing less than 20 kg nitrogen/ha.year. The potential for N2 fixation was not attained during this period due to below-average rainfall and high soil NO3-N accumulation because of poor utilisation by the preceding wheat crop. Increased soil NO3-N due to residual from fertiliser N applied to the preceding wheat crop further reduced N2 fixation. A simple soil nitrogen balance indicated that at least 60% of crop nitrogen must be obtained from N2 fixation to avoid continued soil nitrogen loss. This did not occur in most years. The generally negative soil nitrogen balance needs to be reversed if chickpea is to be useful in sustainable cropping systems although it is an attractive cash crop. Sowing time and zero tillage practice, possibly combined with more appropriate cultivars, to enhance chickpea biomass, along with low initial soil NO3-N levels, would provide maximum N2 fixation.


1993 ◽  
Vol 33 (2) ◽  
pp. 245 ◽  
Author(s):  
PG Tow

The persistence and water use efficiency of Digitaria eriantha spp. eriantha and Hunter river lucerne were compared on red solodic soil with a hardsetting surface and poor internal drainage, on the North- West Slopes of New South Wales. After prolonged watering, the profile was wet to a depth of 48 � 1.5 cm, with an available moisture store of 90 mm. Over 3 years, persistence of digitaria was excellent. The population of lucerne was reduced following flooding at summer temperatures, Dry matter production of nitrogen (N) fertilised digitaria per mm warm season rainfall was similar to that of tropical grasses adapted to comparable rainfall environments in subtropical Queensland. Lucerne dry matter per mm rainfall was only about half that of digitaria (3.2 v. 6.3 kg). Lucerne grew well in mixture with digitaria except under prolonged wet soil conditions in summer. Artificial solodic profiles were constructed in the glasshouse to compare digitaria and lucerne in monoculture and mixture under varying temperature, moisture, and N regimes. Lucerne showed sensitivity to both high and low moisture levels at summer temperatures but performed very well at spring temperatures and moderate moisture levels where the mean evapotranspiration ratio was 400 g water per g dry matter. Water use efficiency was higher in digitaria than in lucerne, except at spring temperatures without added N. Water use efficiency of the mixture was always similar to that of the most efficient monoculture of the particular treatment.


1988 ◽  
Vol 15 (6) ◽  
pp. 815 ◽  
Author(s):  
GC Wright ◽  
KT Hubick ◽  
GD Farquhar

Variation in water-use efficiency (W, g of total dry matter produced/kg water used), and its correlation with cultivar isotope discrimination in leaves (Δ) was assessed in peanut plants grown in small canopies in the field. Plants were grown in separate minilysimeters that were both embedded in the ground and positioned above the crop. Differences among cultivars were found in W and � and the relationship between W and Δ was compared for plants grown in open and closed canopies. Genetic variability in W in plants grown in the field under non-limiting water conditions was demonstrated, with Tifton-8, of Virginia habit, having the highest W (3.71 g/kg) and Rangkasbitung, an Indonesian cultivar of Spanish habit, the lowest (2.46 g/ kg). Variability in W was due to variation in total dry matter production more than that of water use. A strong negative correlation was found between Δ and W, and also between Δ and total dry matter. The relationship between whole plant W, including roots, and Δ was stronger than that between shoot W, without roots and Δ. The improvement occurred because of variation among cultivars in the root to shoot ratio. This highlights the importance of taking account of root dry matter in studies concerning W. There were significant differences in W and Δ between plants in pots above-ground compared to pots in the ground, with above-ground plants having significantly lower values of both W and Δ. The ranking of W and Δ among cultivars was not affected by the contrast in environment, which suggests these parameters are under strong genetic control. Total above-ground dry matter yield at maturity was negatively correlated with Δ, while pod yield was not. It appears a negative association between harvest index and Δ may exist; however not all cultivars used in this and other studies follow this response. Both water-use efficiency, Wand total dry matter production are negatively correlated with Δ in leaves of peanut plants grown in small canopies in the field. Measurement of Δ may prove a useful trait for selecting cultivars with improved W and total dry matter yield under field conditions.


Author(s):  
Fernando J. da Silva Júnior ◽  
José A. Santos Júnior ◽  
Manassés M. da Silva ◽  
Ênio F. de F. e Silva ◽  
Edivan R. de Souza

ABSTRACT Hydroponic cultivation using saline waters is an alternative for agricultural production, especially in the cultivation of vegetables. Therefore, the present work was conducted with the objective of evaluating the water consumption, water use efficiency and water content, as well as dry matter partitioning of chives (Allium schoenoprasum), cv. Todo Ano Evergreen – Nebuka exposed to six levels of nutrient solution salinity (1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 dS m-1), applied at two circulation frequencies (twice a day at 8 and 16 h; and three times a day - at 8, 12 and 16 h). The level in the nutrient solution reservoir, which decreased according to the water consumption by plants, was replaced with the respective saline water (Experiment I) and supply water (Experiment II). Both experiments used a completely randomized design, in a 6 x 2 factorial scheme, with five replicates. It was observed that increased circulation frequency and the use of supply water in the replacement mitigated the effects of salinity on water consumption, water use efficiency and water content in the plant. However, with the increase in nutrient solution electrical conductivity, dry matter allocation in the roots increased, to the detriment of the shoots.


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