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Straw residues left in the field include the crop stubbles, stems and leaves, part of the crushed straw remained in the field under the condition of reasonable harvest stubble. Besides collectable straw returned to field directly, leaving the straw residues in the field is the basic form of direct-application of straw into fields and this phenomenon could be widely seen throughout almost all the cropland in China. Researches on quantitative estimation of straw residues are of great significance to estimate the amount of collectable straw resources, evaluate the land productivity quantitatively and to make planning of direct-application of straw into fields etc. Formulas for estimating the quantity of straw residues left on the field were derived in this research. Five parameters were used in this study including average plant height, harvesting stubble height, leaf ratio, leaf fall rate, crops stalk loss ratio of mechanical collector. Parameters that estimated the quantity of wheat, corn and rice straw residues left in the field were determined by field surveys and literature analysis through selecting a large number of experimental data and survey data. The results showed that the amount of straw residues left on the field would increase gradually with the growing mechanical harvesting area. Total amount of straw returning to the field of China would increase to 600 000 000 t in ten years and that was 60% of the total production of crop straw. If the amount of collectable straw returning to field increased at the same time, the proportion and level of straw returning to the field would reach the level comparable to developed countries such as USA and Japan etc. In 2013, the amount of straw residues left on the field of three major crops of wheat, corn and rice in China was 71 069 200, 45 434 800 and 63 929 500 t, respectively. Straw residues left on the field of the whole nation was 253 300 800 t in the cropped area, and straw residues left on the field for the average per hectare of the sown area was 1.87 t. To meet the minimum requirement of the basic amount of straw residues directly returning to the field, this number should increase by 60% at least. Meanwhile, it should be expanded by 140% at least to meet the regular amount of straw residues directly returning to the field. The final part of this paper showed future needs for such research to calculate the quantity the straw residues applied into the field. The first is to carry out the extensive measure and calculation in the field, thus promotes the accuracy of the quantitative estimation parameters of straw residues of wheat, corn and rice, especially that of the harvesting stubble height and crops straw loss ratio of mechanical collector. The second is to carry out the quantitative estimation research on the straw residues of the economic crops as cotton, bean and rape etc., and further establish parameters of quantitative estimation of national major grain and economic crops' straw residues directly applied into the field. The third is to establish the parameters of quantitative estimation of regional straw residues directly applied into the field, and then gradually extend to apply this method to all the rest regions. [ABSTRACT FROM AUTHOR]

To preparing a new high-performance edible film, the edible films were made from whey protein concentrate (WPC) and chitosan (CS). The modified treatment with assistance of ultrasonic/microwave group was carried out. According to pre-test, the optimal ultrasonic power 90 W, microwave power 300 W, modified temperature 30°C, the edible films were prepared using WPC: CS=6:6, namely, whey protein concentrate 1.5 g and chitosan (CS) 1.5 g, sorbitol concentration 3 g, pH value 5. The results showed that water vapor permeability (WVP) of the edible films modified with assistance of ultrasonic/microwave was 1.18×10-13 g/(cm·s·Pa), lower than that of the control group (1.64×10-13 g/(cm·s·Pa)), in other words, water vapor permeability modified with assistance of ultrasonic/microwave group, was reduced by 27.9%, by contrast with ultrasound and microwave group water vapor permeability was reduced by 13.4% and 8.9%, respectively; oxygen permeability (OP) of the edible films modified with assistance of ultrasonic/microwave was 1.09×10-5 cm3/(m2·d·Pa), which was lower than 2.1×10-5 cm3/(m2·d·Pa) of the control group, namely, oxygen permeability was reduced by 48.1%, by contrast with ultrasound and microwave group oxygen permeability was reduced by 27.3% and 25.9%, respectively. The results showed that ultrasonic/microwave assisting treatment can reduce water vapor permeability and oxygen permeability of blend films of whey protein concentrate and chitosan. The paper analyzed the effects of factors on the tensile strength, elongation at break, transmittance, water vapor permeability and oxygen permeability by single factor experiments. Those factors included film-forming ratio WPC:CS, adding quantity of sorbitol (as plasticizer), the pH, and the time of ultrasonic/microwave assisting treatment. The optimal technology parameters were WPC:CS=5.8:6.2, sorbitol concentration 0.021 g/mL, pH value 5.13, and ultrasonic/microwave assisting treatment time 5 min; and under the conditions, the blend films exhibited good physical properties, and transmittance was 60.23%, WVP was 1.22×10-13 g/(cm·s·Pa), OP was 1.29×10-5 cm3/(m2·d·Pa), tensile strength was 20.53 MPa and elongation at break was 58.91%. According to the optimization results, WPC/CS edible films were prepared and performance test was executed. The measured average values from three parallel verification experiments were: Tensile strength (TS) 23.45 MPa, water vapor permeability 1.34×10-13 g/(cm·s·Pa), elongation at break 57.6%, oxygen permeability 1.15×10-5 cm3/(m2·d·Pa) and transmittance 61.5%. The relative error of transmittance was minimum which was only 2.07%, and the relative error of water vapor permeability was maximum which was 5.65%. It was found that the relative error experiment results can be used to predict. The results can provide a reference for the development of a new edible film. [ABSTRACT FROM AUTHOR]