It is important to study the law of water distribution in potted soil and the appropriate irrigation methods for improving the level of water-saving irrigation in greenhouse cultivation. In this study, pepper was taken as the experimental crop. Two kinds of drip irrigation models (root zone infiltrating irrigation and surface drip irrigation) and two kinds of irrigation emitter arrangements (a 3 × 120° distribution and a 2 × 180° distribution) were used to plot out the distribution pattern of soil water in a potted planting environment for two kinds of soils (Yunnan red loam and yellow-sand soil). Then, the growth indices of peppers were compared. The results showed that drip irrigation models and soil types had a significant interactive effect on soil water distribution (P < 0.01); in Yunnan red loam, the matric potential played a major role in the transport of irrigation water, while in yellow-sand soil, gravitational potential played a major role. Under root zone infiltrating irrigation, the high-water-content distribution area of the two types of soil is more continuous and balanced than that of surface drip irrigation, and the balance of water distribution of the yellow-sand soil is better than that of the red loam. In Yunnan red loam, the growth indices of peppers (plant height, stem diameter, fruit fresh weight, fruit dry weight, and similarly hereinafter) increased by 12.9%, 14.3%, 46.1%, and 36.8%, respectively; in yellow-sand soil, the growth indices under root zone infiltrating irrigation were 31.7%, 25.9%, 26.9%, and 35.3%, which were lower than those of surface drip irrigation. The experiment shows that in a greenhouse potting environment, Yunnan red loam with root zone infiltrating irrigation offers more water-saving potential. The results provide a theoretical basis and data support for the rational selection of drip irrigation models for facility agriculture in Yunnan.

Abstract. In this study, an equivalent mechanical model was established for the clogging induced by soil suction under negative pressure during root-zone infiltration irrigation in a crop-free pot, and a state diagram was plotted for the clogging process induced by a single soil suction factor under negative pressure. Three groups of impact factor experiments were conducted using three different emitters: a flow-adjustable emitter with eight horizontal outlets (emitter L), a flow-adjustable emitter with two vertical outlets (emitter Q), and an anti-clogging material wrapped around the outer surface of emitter L (emitter K). The first group of experiments investigated the influence of irrigation pressure, the variation of irrigation pressure (range of 0.02 to 0.12 MPa), and the amount of sediment inside emitter L in Yunnan laterite. For the second group of experiments, two soil types (Yunnan laterite and yellow sand), two single-event irrigation volumes (170 and 250 mL), and two numbers of irrigation events (8 and 16) were used to quantitatively analyze the sediment content in emitter L. The third group of experiments used emitters L, Q, and K and involved quantitative analysis of the clogging differences in the different emitter types with two soil types (Yunnan laterite and yellow sand) and two numbers of irrigation events (24 and 64). Statistical analysis showed that irrigation pressure, soil type, irrigation pattern, and emitter type were significant (p &lt; 0.05) for the amount of sediment due to negative suction inside the emitter. The results demonstrate that emitter clogging induced by negative pressure tends to first decrease and then increase with increasing irrigation pressure. The amount of sediment that accumulates within an emitter is influenced by both the soil suction effect under negative pressure as well as soil flushing under positive pressure. Within emitter L, clogging induced by soil suction under negative pressure was more likely to occur when using Yunnan laterite rather than yellow sand soil. When both soil types were used in the test, emitter L was observed to be more prone to clogging induced by negative pressure compared to emitter Q, whereas emitter K exhibited the best anti-clogging performance. This study provides a quantitative account of the factors associated with clogging induced by negative pressure, and it provides a theoretical and experimental basis for gaining an in-depth understanding of emitter clogging during root-zone infiltration irrigation in Yunnan laterite. Keywords: Emitter, Negative-pressure clogging, Pot environment, Root-zone infiltration irrigation, Yunnan laterite.

Understanding the water content variations in Yunnan laterite (red loam soil, SR) in small-scale environments and exploring the potential for crop water-use efficiency (WUE) improvement are crucial for improving water-saving irrigation technologies used in greenhouse agriculture in Yunnan, China. In this study, a closed-loop model for calculating soil water in greenhouse potted cultivation was established based on water conservation. A Yunnan SR, yellow sand soil (SY), and a 1:1 SR–SY mixture (SM) subjected to root-zone micro-irrigation or surface-drip irrigation were experimentally examined to compare their water content variations and pepper WUEs. The results showed that the soil type and soil type–irrigation mode interaction had significant effects on both soil evaporation and pepper WUE, and that the variations in soil evaporation with respect to time can be expressed using a cubic polynomial function. In small-scale greenhouse cultivation, IG has good water-saving potential and is suitable for the SR (which has a better water-retention capacity), whereas IM is more suitable for the SY (which has a better water-penetration capacity). Mixing certain proportions of the SY into the SR will effectively impact the water content variations and crop WUE and provide opportunities for further improving the water-saving efficiency.