Insentek Sensor: An Alternative to Estimate Daily Crop Evapotranspiration for Maize Plants

Estimation of ground-truth daily evapotranspiration (ETc) is very useful for developing sustainable water resource strategies, particularly in the North China Plain (NCP) with limited water supplies. Weighing lysimetry is a well-known approach for measuring actual ETc. Here, we introduced an alternative to lysimetry for ETc determination using Insentek sensors. A comparison experiment was conducted for maize plants at Xuchang Irrigation Experiment Station, in the NCP, in 2015 and 2016. Insentek ETc was evaluated using data on clear days and rainy days independently. We found that daily ETc increased gradually from VE (emergence) to VT (tasseling) stages, peaked at the R1 (silking) stage with the highest value of 7.8 mm·d−1, and then declined until maturity. On average, cumulative total of lysimetric ETc was 19% higher than that of Insentek ETc. The major depth of soil water extraction might be 60 cm for maize plants on lysimeters according to soil water depletion depth monitored by Insentek sensors. Daily ETc significantly related to soil water content (SWC) in topsoil (0–30 cm) in an exponential function (coefficients of determination (R2) = 0.32–0.53), and to precipitation (Pre) in a power function (R2 = 0.84–0.87). The combined SWC (0–30 cm)–Pre–ETc model may offer significant potential for accurate estimation of maize ETc in semi-humid environment of the NCP

Preparation and Evaluation of Self-Assembled Porous Microspheres–Fibers for Removal of Bisphenol A from Aqueous Solution

A novel design of PP-<i>g</i>-DMAEMA/PM composite fiber as an efficient adsorbent was demonstrated by combining graft polymerization of dimethylaminoethyl methacrylate (DMAEMA) with self-assembled modification of porous microspheres (PMs) on the surface of polypropylene (PP) fiber. The structure and composition of the adsorbent was characterized by BET, XPS, FTIR, DSC, FESEM, and water angle. The kinetics and isotherm data indicated that the adsorption of bisphenol A (BPA) could be well-fitted by a pseudo-second-order kinetic model and the Langmuir isotherm, respectively. The thermodynamic studies indicated that the adsorption reaction was a spontaneous and exothermic process. Because of the π–π interactions and hydrogen bonds between BPA and PP-<i>g</i>-DMAEMA/PM, the resulting fiber obtained a higher adsorption amount (44.43 mg/g) of BPA. The presence of NaCl in the solution could facilitate the adsorption process, whereas the strong acid or strong alkali conditions and higher temperature of the solution were unfavorable. Besides, the obtained fiber reusability without obvious deterioration in performance was demonstrated by at least seven repeated cycles

Impacts of Steel-Slag-Based Silicate Fertilizer on Soil Acidity and Silicon Availability and Metals-Immobilization in a Paddy Soil

<div><p>Slag-based silicate fertilizer has been widely used to improve soil silicon- availability and crop productivity. A consecutive early rice-late rice rotation experiment was conducted to test the impacts of steel slag on soil pH, silicon availability, rice growth and metals-immobilization in paddy soil. Our results show that application of slag at a rate above higher or equal to 1 600 mg plant-available SiO₂ per kg soil increased soil pH, dry weight of rice straw and grain, plant-available Si concentration and Si concentration in rice shoots compared with the control treatment. No significant accumulation of total cadmium (Cd) and lead (Pb) was noted in soil; rather, the exchangeable fraction of Cd significantly decreased. The cadmium concentrations in rice grains decreased significantly compared with the control treatment. In conclusion, application of steel slag reduced soil acidity, increased plant–availability of silicon, promoted rice growth and inhibited Cd transport to rice grain in the soil-plant system.</p></div

Incorporation of Manure into Ridge and Furrow Planting System Boosts Yields of Maize by Optimizing Soil Moisture and Improving Photosynthesis

A sustainable management strategy of soil fertility and cropping system is critical to guaranteeing food security. However, little is known about the effects of soil amendment strategies on crop growth via regulating soil moisture and photosynthesis in a ridge and furrow cropping system. Here, field experiments were carried out in 2017 and 2018 in semi-arid areas of Loess Plateau, northwest China to investigate the effects of integrated use of ridge and furrow planting and manure amendment on grain yields of maize. Four treatments were designed: CK (flat planting with 100% chemical fertilizer), RFC (ridge and furrow planting with 100% chemical fertilizer), RFR (ridge and furrow planting with 100% control-released fertilizer), and RFM (ridge and furrow planting with 50% manure fertilizer + 50% N fertilizer). On average, RFM increased photosynthetic rates (Pn) by 74%, followed by RFR by 47%, and RFC by 26%, compared to CK. Also, stomatal conductance (Cd), transpiration rates (Tr), and intercellular CO2 concentration (Ci) were highest with RFM, followed by RFR and RFC. Averaged across the two years, RFM conserved 10% more soil water storage (SWS) than CK did at harvest, followed by RFR with an increment by 8%. However, RFC consumed more soil water than CK did, with its ETc 8% higher than CK. Consequently, spring maize treated with RFM suffered less drought stress, especially in 2017 when precipitation was insufficient. On average, grain yields and water use efficiency of RFM were increased by 18% and 27%, compared to CK. Structural equation modeling analysis showed that there existed significant positive correlation between SWS in top layers and grain yields, while SWS in deep layers had negative effects on grain yields. In conclusion, the incorporation of manure into ridge and furrow planting system can be an efficient agronomic practice to improve plant photosynthesis, optimize soil moisture, and boost grain yields in semi-arid areas of Loess Plateau, northwest China

BCR extraction concentration of Cr, Cd and Pb in steel slag used in the field experiment.

<p>BCR extraction concentration of Cr, Cd and Pb in steel slag used in the field experiment.</p

BCR sequential extraction method of heavy metal in steel slag.

<p>BCR sequential extraction method of heavy metal in steel slag.</p

Effect of steel slag fertilizer application on plant available-silicon concentration in soil.

<p>Data are means of three replicates. Mean values followed by different letters (a, b, c) in the same season are significantly different (<i>P</i>< 0.05).</p

Soil basic characteristics and total heavy metal concentrations in the soil and steel slag used in the field experiment.

<p>Soil basic characteristics and total heavy metal concentrations in the soil and steel slag used in the field experiment.</p

Effect of steel slag fertilizer application on silicon concentration in rice straw.

<p>Data are means of three replicates. Mean values followed by different letters (a, b, c) in the same season are significantly different (<i>P</i>< 0.05).</p

Effect of steel slag fertilizer application on soil pH.

<p>Data are means of three replicates. Mean values followed by different letters (a, b, c) in the same season are significantly different (<i>P<</i> 0.05).</p