Impact of Land Configuration and Strip-Intercropping on Runoff, Soil Loss and Crop Yields under Rainfed Conditions in the Shivalik Foothills of North-West, India

Maintaining sustainable crop production on undulating, sloppy, and erodible soils in Shivalik foothills of North-west India is a challenging task. Intercropping is accepted as a highly sustainable system to reduce soil erosion and ensure sustainable production by making efficient use of resources. Field experiments were conducted in the rainy season (July to September) during 2015, 2016, and 2017 to evaluate the effect of land slopes and maize and cowpea strip-intercropping on productivity and resource conservation at the Regional Research Station, Ballowal Saunkhri located in the Shivalik foothills. During three years of experimentation, a total of 23–26 runoff events were observed in the maize crop grown in the rainy season. The results from this 3-year field study indicate that maize grain yield was significantly higher on a 1% slope and cowpea on a 2% slope. This accounted for significantly higher net returns (US$ 428 ha−1) with a benefit-cost (BC) ratio of 2.0 on a 1% slope. Runoff, soil, and nutrient losses were higher on a 3% slope as compared to 1% and 2% slopes. N, P, and K loss on a 3% slope were 3.80, 1.82, and 4.10 kg ha−1 higher, respectively than a 1% slope. The adoption of a strip-intercropping system with a 4.8 m maize strip width and 1.2 m cowpea strip width resulted in significantly higher maize equivalent yield than sole maize and other strip-intercropping systems. This system showed the highest land equivalent ratio value (1.24) indicating a 24% yield advantage over sole cropping systems of maize and cowpea, and fetched the highest net returns (US$ 530 ha−1) with a benefit-cost ratio (BC ratio) of 2.09. This system also reduced runoff and soil loss by 10.9% and 8.3%, respectively than sole maize crop. On all the land slopes, maize and cowpea strip-intercropping systems showed a significant reduction in N, P, K, and organic carbon loss as compared to sole maize. Thus, on sloping land, the maize and cowpea strip-intercropping system decreases surface runoff, soil, and nutrient loss, and increases yield and income of the farmers as compared to a sole maize crop.

Numerical Implementation of Drop Spin and Tilt Method For Five-Axis Tool Positioning For Tensor Product Surfaces

This paper presents an extension of multi point machining technique, called the Drop Spin and Tilt (DST) method, that spins the tool on two axes, allowing for the generation of multiple contact points at varying distances around the first point of contact. The multiple DST second points of contact were used to manually generate a toolpath with uniform spacing between the two points of contact. The original DST method used a symbolic algebra package to position the tool on a bi-quadratic surface; our extension is a numer- ical solution that allows positioning a toroidal tool on a tensor product Bezier surface. Further, we investigate the spread of possible second points of contact as the tool is spun around these two axes, demonstrating the feasability of using the method to control the machining strip width.

The pressure relief protection effect of different strip widths, dip angles and pillar widths of an underside protective seam

To design underside protective seam strip layout. Similarity model experiments, numerical simulations and theoretical calculations are used to quantitatively study the pressure relief protection effect of different strip widths, dip angles and coal pillar widths of a thin underside protective seam under deeply buried conditions. The optimal strip width range is obtained according to the change law of strain during the mining process of the underside protective seam in a similar model experiment. The change law of the expansion of the protected coal seam is obtained and the fitting surfaces among the dip angle and strip width of the coal seam with the protection distance and pressure relief angle along the strike and dip of the protected coal seam are established according to the numerical simulation results of underside protective seam mining. It is concluded that the best pressure relief effect can be achieved when the dip angle is 16.7° and the strip width is 70 m. According to the stability threshold of coal pillars considered in strip mining theory, the coal pillar width is calculated to be 50 m. Similarity model experiments and numerical simulations of protected coal seam mining verify the pressure relief effect of the designed protective seam strip width and pillar width. A calculation method of the protective seam strip width, position and pillar width required by the specific width of the protected seam is proposed.

Investigation of Coalescence-Induced Droplet Jumping on Mixed-Wettability Superhydrophobic Surfaces

Coalescence-induced droplet jumping has received more attention recently, because of its potential applications in condensation heat transfer enhancement, anti-icing and self-cleaning, etc. In this paper, the molecular dynamics simulation method is applied to study the coalescence-induced jumping of two nanodroplets with equal size on the surfaces of periodic strip-like wettability patterns. The results show that the strip width, contact angle and relative position of the center of two droplets are all related to the jumping velocity, and the jumping velocity on the mixed-wettability superhydrophobic surfaces can exceed the one on the perfect surface with a 180° contact angle on appropriately designed surfaces. Moreover, the larger both the strip width and the difference of wettability are, the higher the jumping velocity is, and when the width of the hydrophilic strip is fixed, the jumping velocity becomes larger with the increase of the width of the hydrophobic strip, which is contrary to the trend of fixing the width of the hydrophobic strip and altering the other strip width.

Strip-width determines competitive strengths and grain yields of intercrop species in relay intercropping system

Maize/soybean relay intercropping system (MSR) is a popular cultivation method to obtain high yields of both crops with reduced inputs. However, in MSR, the effects of different strip widths on competitive strengths and grain yields of intercrop species are still unclear. Therefore, in a two-year field experiment, soybean was relay-intercropped with maize in three different strip-width arrangements (narrow-strips, 180 cm; medium-strips, 200 cm; and wide-strips, 220 cm), and all intercropping results were compared with sole maize (SM) and sole soybean (SS). Results showed that the optimum strip-width for obtaining high grain yields of maize and soybean was 200 cm (medium-strips), which improved the competitive-ability of soybean by maintaining the competitive-ability of maize in MSR. On average, maize and soybean produced 98% and 77% of SM and SS yield, respectively, in medium-strips. The improved grain yields of intercrop species in medium-strips increased the total grain yield of MSR by 15% and land equivalent ratio by 22%, which enhanced the net-income of medium-strips (by 99%, from 620 US $ ha−1 in wide-strips to 1233 US $ ha−1 in medium-strips). Overall, these findings imply that following the optimum strip-width in MSR, i. e., strip-width of 200 cm, grain yields, and competitive interactions of intercrop species can be improved.

Strip width ratio expansion with lowered N fertilizer rate enhances N complementary use between intercropped pea and maize

Maize (Zea mays L.)/pea (Pisum sativum L.) strip intercropping is considered a promising cropping system to boost crop productivity. The 3-year (2009–2011) field experiment was conducted at Wuwei, northwest China, with two maize to pea strip width ratios (80:80 cm and 120:80 cm), each under three N fertilizer rates (0, 90 and 135 kg N ha−1 for pea, and 0, 300, and 450 kg N ha−1 for maize). The results showed that expanding maize to pea strip width ratio from 80:80 cm to 120:80 cm coupled with a reduction of N fertilizer rate intensified N competition and improved N compensation. The apparent N recovery and N utilization efficiency of intercropped pea with strip width ratio of 120:80 cm were increased by 8.0% and 8.9% compared to strip width ratio of 80:80 cm. Compared to high N rate, the two indicators of intercropped pea with lowered N rate were increased by 10.0% and 6.0%. For intercropped maize, the two indicators were increased by 6.8% and 5.1%, with strip width ratio of 120:80 cm compared to 80:80 cm. Also, they were improved by 9.7% and 11.5%, with lowered N rate compared to high N rate. Consequently, the grain yield of pea and maize in the 120:80 cm pattern was improved by 11.9% and 7.7% compared to 80:80 cm. We concluded that expanding maize to pea strip ratio coupled with N fertilizer reduction can optimize N complementary use.