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Dryland water resource scarcity has been the most challenging issue facing the continuous development of irrigated agricultural systems. Although drip irrigation, especially subsurface drip irrigation (SDI) technology, reduced water loss from soil evaporation and increased water use efficiency (WUE), drip emitter with pumps brought large electric energy consumption and management cost, limiting its application for smallholders in dryland. Therefore, a new subsurface ceramic emitter (SCE) without using pumps, which consisted of a porous ceramic diaphragm, plastic washers, and plastic shells, was designed for smallholders in this study. Then its application effects were estimated using hydraulic, soil bin, pot, and field experiments. The results showed that the discharge of SCE in the air had a positive linear relationship with the working water head. The discharge of SCE in soil presented a power function relationship with the working water head, and the discharge exponent was 0.40. It was recommended that SCE should install at flat farmland with a topographic slope less than ± 5‰ to acquire an acceptable coefficient of uniformity (CU) under the working water head of more than 40 cm. A field experiment in Northwest China showed that SCE with a working water head of 60 cm created a suitable water moisture environment and CU, improving fruit yield and WUE of wolfberry. This provided an alternative irrigation method using SCE with a lower working water head for smallholders in dryland while ensuring a good CU. [ABSTRACT FROM AUTHOR]

Biochar is a widely used soil amendment that has positive effects on improving soil quality, promoting resource efficiency of agricultural production, and reducing environmental pollution. In order to better play the potential role of biochar in agricultural production and optimize the addition strategies of biochar. This study conducted extraction analysis, random forest simulation and win-win analysis on 381 datasets from 63 studies around the world. The results showed that the addition of biochar increased crop yield by 14.45%, water use efficiency (WUE) by 14.28% and nitrogen use efficiency (NUE) by 13.97%. Among them, the key factors affecting the addition effect of biochar were soil organic carbon (SOC), soil total nitrogen (Soil-TN), soil bulk density, biochar carbon content (Biochar-TC) and biochar carbon nitrogen ratio (Biochar-C:N). In addition, the application of biochar with less carbon content (TC ≤ 200 g kg−1, C:N between 50 and 100) in the soil with large bulk density (>1.4 g cm−3) and low nutrients (SOC between 10 and 15 g kg−1, TN ≤ 0.5 g kg−1) could better achieve a win-win situation in crop productivity and resource use efficiency. Our findings can help to formulate the addition strategies of biochar. [Display omitted] • Biochar improves crop yield, water and nitrogen use efficiency. • Soil and biochar properties are critical for biochar's addition effect. • The effect of adding biochar to low nutrient soils is better. • The effect of adding biochar with low carbon content is better. [ABSTRACT FROM AUTHOR]

• HYDRUS-2D was used for estimating water balance components and water productivity. • Suitable water head of subsurface irrigation using ceramic emitters (SICE) was 0.4 m. • SICE reduced irrigation amount and water loss by evaporation and deep percolation. • SICE enhanced tomato yield, water productivity and fruit quality in greenhouse. Greenhouses are widely used in Northwest China, especially for tomato, which is the dominant crop. Subsurface irrigation with ceramic emitters (S I C E) is a new water-saving technology for continuous low-rate water supply at constant soil moisture. However, a lack of knowledge still existed to define the suitable working water head for S I C E to decrease water loss and promote tomato production, fruit quality, and water productivity. In this study, a greenhouse experiment was conducted during spring and autumn cultivation periods under S I C E for five working water heads of 0.1 m to 0.5 m with intervals of 0.1 m and subsurface drip irrigation (S D I). The verified HYDRUS-2D model evaluated water balance components and water productivity. A structural equation model (S E M) was developed to determine interactive impacts of S I C E and meteorological conditions in greenhouse on tomato yield, fruit quality, and water productivity. The results showed that S I C E with a working water head of 0.4 m could be recommended, which created a suitable soil water content of the root zone within 70%–80% of field capacity (F C), resulting in a reduction of water loss from actual evaporation (E a) and deep percolation (D P) by 12.32% and 21.88% respectively relative to S D I. Fruit weight, yield, water use efficiency (W U E), and irrigation water use efficiency (I W U E) were increased by 8.96%, 8.03%, 19.44%, and 16.05% respectively compared to S D I. Moreover, soluble sugar, organic acid, lycopene, vitamin C, and sugar acid ratio were enhanced by 2.41%, 12.19%, 14.40%, and 2.67% under S I C E with the suggested working water head respectively compared with S D I. We recommended that supplemental lighting combined with S I C E in autumn cultivation was necessary to ensure tomato production and fruit quality. This study provides an alternative water-saving irrigation method for greenhouse growers to maintain tomato yield and fruit quality in Northwest China. [ABSTRACT FROM AUTHOR]