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The global phosphate (P) rock shortage has become a significant challenge. Furthermore, the misalignment between crops, soil, and P usage exacerbates P rock wastage in agriculture. The distinctions among various types of phosphorus fertilizers influence the phosphorus cycle, which subsequently impacts biomass, the number of grains per ear, the weight of a thousand grains, and, ultimately, the overall yield. In a four-year field experiment conducted from 2017 to 2021, we assessed the impact of various P fertilizer types on crop yield in a continuous wheat–maize rotation system. Prior to planting the crops, P fertilizers were applied as base fertilizers at a rate of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Additionally, nitrogen (N) was applied at rates of 120 kg ha−1 for wheat and 180 kg ha−1 for maize. The P fertilizers used included ammonium dihydrogen phosphate, ammonium polyphosphate, calcium–magnesia phosphate, ammonium phosphate, and calcium superphosphate. Urea was used as the N fertilizer with a split application—60% at planting and 40% at the jointing stage for wheat or the V12 (twelve leaf collar) stage for maize. The results showed that different P fertilizers increased the average yield of wheat and maize by 21.2–38.0% and 9.9–16.3%, respectively. It was found that ammonium polyphosphate, calcium superphosphate, and monoammonium phosphate were more suitable for application in a summer maize–winter wheat rotation system on loess soil. [ABSTRACT FROM AUTHOR]

The processes coupled with carbon and water exchange are linked to crop assimilation, water consumption, controlling crop growth and development, and ultimately determining crop yield. Therefore, studying the characteristics of crop water constraints and their controlling factors at multiple scales is of great significance for regional and global food production stability and food security. Employing field observations and a comprehensive literature review, this study investigates the maximum water-use efficiency of wheat and its governing factors at both leaf and canopy (ecosystem) scales. The results demonstrate remarkable consistency and well-defined boundaries in maximum water-use efficiency across diverse climate regions and wheat varieties, both at the leaf and agricultural ecosystem scales. At the leaf scale, the maximum water-use efficiency of wheat was 4.5 μg C mg−1 H2O, while for wheat agricultural ecosystems, on a daily scale, the maximum water-use efficiency was 4.5 g C kg−1 H2O. Meanwhile, the maximum water-use efficiency of wheat agricultural ecosystems decreased continuously with increasing time scales, with values of 6.5, 4.5, 3.5, and 2 g C kg−1 H2O for instantaneous, daily, weekly, and monthly scales, respectively. Environmental factors, primarily vapor pressure deficit, light, and soil water content, exert significant control over leaf-level water-use efficiency. Similarly, the maximum water-use efficiency of agricultural ecosystems fluctuates in response to daily variations in meteorological elements. C3 crops like wheat exhibit remarkable resilience in their carbon–water exchange patterns across diverse environmental conditions. The findings in the current research can serve as a reference for improving crop water-use efficiency. [ABSTRACT FROM AUTHOR]

Agricultural drought often refers to water deficit in soil caused by a shortage of precipitation during a specific period in crop growing season, thus leading to final crop production failure. However, soil water content during planting may be related to the final yield of crop. Therefore, the soil water content at planting could have a great impact on determining whether agricultural drought occurs during crop growth and development. In the current study, we used soil water content at planting at 0–50 cm depth, the spring wheat (Triticum aestivum L.) yield from 1987 to 2011, and precipitation from 1971 to 2011 at Dingxi, Gansu Province, China, intending to quantify the influence of soil water content at planting on determining agricultural drought for rainfed spring wheat. The response of spring wheat yield to growing season precipitation comprised two different linear relationships defined by whether the soil water content at planting was greater or less than 100 mm. With the identical amount of soil water content at planting and precipitation during main growth period, a higher soil water content at planting resulted in a greater spring wheat yield. Soil water content at planting was more effective than growing season precipitation for increasing spring wheat yield. According to the probability distributions of soil water content during planting and growing season precipitation, we concluded that 28.6% of the years studued involved agricultural drought for rainfed spring wheat in the Dingxi of Gansu province, China. This analysis, which quantified the relative importance of soil water content at planting (29.97 kg ha−1 per mm) and during growing season precipitation (12.21 kg ha−1 per mm) to determine yield and agricultural drought occurrence for spring wheat, suggests that improving the amount of soil water storage before crop planting is an important way to deal with agricultural drought. [ABSTRACT FROM AUTHOR]

In order to explore and validate the impact of further climate change on spring wheat growth and yield, and to obtain basic features of spring wheat's response to warming and precipitation change, an infrared temperature-increasing simulation experiment was conducted in Dingxi of Gansu Province, Northwest China. With the applications of free air temperature increased system (FATI) and water control devices, different precipitation and air temperature gradients were installed to simulate the effects of climate change on spring wheat growth. The impacts of warming and precipitation change on growth and yield of spring wheat were also analyzed. The results showed that warming of 2°C decreased the plant height of spring wheat by 8.55% under normal precipitation condition, and warming of 2°C decreased the plant height of spring wheat by 9.65% under the condition of increasing precipitation by 30%. Increasing precipitation by 30% enhanced the plant height of spring wheat by 4.8% under normal temperature condition, and increasing precipitation by 30% enhanced the plant height of spring wheat by 3.56% under warming of 2°C. The plant height of spring wheat under the condition of warming of 2°C and increasing precipitation by 30% was smaller than that under normal temperature and normal precipitation condition. On the condition of normal precipitation, warming of 2°C decreased the leaf area index of spring wheat by 28.15%, and on the condition of increasing precipitation by 30%, warming of 2°C decreased the leaf area index of spring wheat by 31.04%. Under normal temperature and warming of 2°C, the effect of precipitation on leaf area index was not very obvious. The leaf area index of spring wheat under warming of 2°C and increasing precipitation by 30% condition was smaller than that under normal temperature and normal precipitation condition. Warming decreased chlorophyll content of spring wheat leaf, and especially after filling stage, the chlorophyll content decreased more significantly. Increasing precipitation by 30% enhanced the chlorophyll content of spring wheat leaf under warming of 2°C. On the conditions of normal precipitation and increasing precipitation by 30%, the dry matter amounts of spring wheat under warming were all smaller than that under normal temperature. Increasing precipitation by 30% was conducive to the accumulation of dry matter under normal temperature and warming. In the vegetative growth stage and reproductive growth stage, under the conditions of normal precipitation and increasing precipitation by 30%, warming had a negative effect on the partition coefficient of the leaves and a positive effect on the partition coefficient of the stem, but increasing precipitation by 30% had a positive effect on the partition coefficient of the leaves and a negative effect on the partition coefficient of the stem. In the reproductive growth stage, under the conditions of normal precipitation and increasing precipitation by 30%, warming had a negative effect on the partition coefficient of the panicle, but increasing precipitation by 30% had a positive effect on the partition coefficient of the panicle. Under normal temperature, increasing precipitation by 30% enhanced yield of spring wheat by 4.89%, spikelet number by 4.92%, grains per panicle by 2.44%, grains weight per panicle by 4.99%, 1000-grain weight by 2.64%, length of panicle by 8.66% and weight of panicle by 4.92%. Under normal precipitation, warming of 2°C decreased yield of spring wheat by 43.26%, spikelet number by 13.11%, grains per panicle by 15.85%, grains weight per panicle by 27.11%, 1000-grain weight by 13.54%, length of panicle by 14.96% and weight of panicle by 24.93%. Water addition had a positive effect on the yield of spring wheat, while warming did not help to improve the yield of spring wheat; even in the case of increasing precipitation, warming still had an adverse effect on yield. The research results can give the theoretical references for the sensitivity and adaptability of spring wheat in semi-arid area of China under global climate change. [ABSTRACT FROM AUTHOR]

The mechanism of the damage process for agricultural drought is very complex, and many factors can affect it. Agricultural drought is the main limiting factor for crop yield in rainfed area. For defining drought occurrence during the crop growth, and predicting crop yield, we used pattern recognition based on meteorological data during growing season and yield data of spring wheat in semi-arid rainfed area in Dingxi, China from 1986 to 2011. Owing to the application of deviation for crop yield from its long-term mean to define agricultural drought, we divided the year pattern into two categories: drought series, and normal series on the basis of 30 percent deviation from the mean wheat yield. The iteration method was then applied in order to find a case wherein the drought could be linearly discriminated from normal category. According to our research, we find the spring wheat yield was affected by various factors. They can be categorized as 1) weather conditions, such as temperature, precipitation; 2) farm management factors and crop variety, such as soil tillage, soil depth, planting density, sowing date, crop protection against pests and diseases, and soil fertility level; 3) soil conditions, such as soil physical properties and soil water content. Measuring or estimating some of these factors was often not feasible, and the influence of some other factors may be considered insignificant or constant in an agrometeorological experimental station. It was therefore weather condition alone that can affect crop yield most significantly. However, it was found that no linear relation existed in any cases based on average temperature and precipitation during the main growing period without taking other factors into a consideration. After rejecting years in which the soil relative water content was more than 55%, we can predict if agricultural drought through establishing a linear equation with two parameters, the average temperature and precipitation during the main growth period for spring wheat. From the research, we also found the best parameter to predict the agricultural drought occurrence and factor that determined spring wheat yield was the precipitation in May. A Predictive Equation for spring wheat yield was also established by the least square method based on the precipitation in May. The predictive equation was simple but useful, and it can forecast spring wheat yield one and half month earlier before wheat harvest. Meanwhile, it should be noted that the predictive equation was established after rejecting the years in which the soil relative water content was more than 55%. We suggested that the agricultural drought differ from meteorological drought. As such, we should use the method much more carefully for quantitative prediction of agricultural drought occurrence and crop yield in future research. [ABSTRACT FROM AUTHOR]

ABSTRACT A homemade resistance probe ( R) and a torroidal probe ( T), which work on different principles to measure conductivity, were used as online sensors to monitor conductivity during the course of emulsion polymerizations of n-butyl methacrylate (BMA). Six batch emulsion polymerizations of BMA (20% solids content) were carried out using sodium lauryl sulfate (SLS) as surfactant. To compare latex stability and conductivity profiles, the SLS concentration was varied (5, 6, 8, 10, 20, and 30 m M). Seven semibatch emulsion polymerizations of BMA (40% solids content) were also run. All semibatch polymerizations had the same seed stage, while different amounts of SLS were fed during the feed stage. During these reactions, the conductivity curves obtained from the two different probes overlapped if the SLS concentration was high enough (20 and 30 m M); on the other hand, the two curves diverged if the SLS concentration was low. Since the final conductivity values obtained from the two probes were not the same in most of the reactions, the ratio between them ( R/ T) was used to correlate conductivity to latex stability. A blender test and turbidity measurements were carried out to estimate the mechanical stability and the electrolyte stability of the prepared latexes, respectively. The results showed that R/ T varied linearly with the latex stability. These results showed that latex stability could be predicted through online conductivity measurements. Moreover, the reason for an observed increase in conductivity during these emulsion polymerization reactions was also investigated. This increase was related to the disappearance of monomer droplets, which demonstrated that the conductivity measurements could also be used to aid in the study the kinetics of the emulsion polymerization process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4001-4013, 2013 [ABSTRACT FROM AUTHOR]