Hebei Plain is the most important agricultural belt in North China. Intensive irrigation, low and uneven precipitation
have led to severe water shortage on the plain. This study is an attempt to resolve this crucial issue of water shortage for
sustainable agricultural production and water resources management. The paper models distributed regional irrigation
requirement for a range of cultivated crops on the plain. Classic crop models like DSSAT- wheat/maize and COTTON2K
are used in combination with pan-evaporation coefficient method to estimate water requirements for wheat, corn, cotton,
fruit-trees and vegetables. The approach is more accurate than the static approach adopted in previous studies. This is
because the combination use of crop models and pan-evaporation coefficient method dynamically accounts for irrigation
requirement at different growth stages of crops, agronomic practices, and field and climatic conditions. The simulation
results show increasing Required Irrigation Amount (RIA) with time. RIA ranges from 5.08×109 m3 to 14.42×109 m3 for
the period 1986~2006, with an annual average of 10.6×109 m3. Percent average water use by wheat, fruit trees, vegetable,
corn and cotton is 41%, 12%, 12%, 11%, 7% and 17% respectively. RIA for April and May (the period with the highest
irrigation water use) is 1.78×109 m3 and 2.41×109 m3 respectively. The counties in the piedmont regions of Mount
Taihang have high RIA while the central and eastern regions/counties have low irrigation requirement.
Staggered canopy system is an effective planting practice for high yield by maximizing light penetration into the canopy of cotton (<i>Gossypium hirsutum L.</i>) plants. Compared with traditional cropping practices, this system produces higher yields in general. A staggered canopy system is constructed by planting two cultivars of different shoot architectures to form a canopy of two leaf layers. Field experiments of four treatments were carried out to determine the optimal pattern of staggered canopy. Solar radiations at different heights in the canopies were measured at a vertical interval of 20 cm between and within rows, using a digital light intensity meter. The optimal planting pattern for high yields consisted of two rows of tall plants bracketing a row of short plants with a wide spacing of 100 cm around the rows of short plants,
which formed a staggered canopy. The available photosynthetic photon flux density in the staggered canopy was higher than in the canopy of conventionally planted field after the canopies were closed. The staggered canopy system allows more light penetration into the canopy than the conventional, where light was deducted sharply by an excessively dense canopy. In addition, wind speeds and CO<sub>2</sub> concentrations inside the staggered canopy were greater than those in the conventional. The staggered canopy has an improved canopy structure compared to a conventional planting practice.
Monte Carlo method has been applied to simulate the hysteresis loops from VSM and MOKE measurement for Ni<sub>x</sub>SiO<sub>2(1-x) </sub>granular films. The simulated results reveal that: (1) The calculated Kerr loops are in good agreement with the experimental data. (2) The anisotropy constant decreases with the increasing packing fraction of Ni clusters; (3) Generally, the difference between the hysteresis loops obtained from VSM and Kerr effect respectively always exists for the finite incident angle. It increases with increasing incident angle. It for strong ferromagnetic films is smaller than those for weak or mixed magnetic films.