Effect of Digestate and Straw Combined Application on Maintaining Rice Production and Paddy Environment

Abstract

Few studies have focused on the combined application of digestate and straw and its feasibility in rice production. Therefore, we conducted a two-year field experiment, including six treatments: without nutrients and straw (Control), digestate (D), digestate + fertilizer (DF), digestate + straw (DS), digestate + fertilizer + straw (DFS) and conventional fertilizer + straw (CS), to clarify the responses of rice growth and paddy soil nutrients to different straw and fertilizer combinations. Our results showed that digestate and straw combined application (i.e., treatment DFS) increased rice yield by 2.71 t ha−1 compared with the Control, and digestate combined with straw addition could distribute more nitrogen (N) to rice grains. Our results also showed that the straw decomposition rate at 0 cm depth under DS was 5% to 102% higher than that under CS. Activities of catalase, urease, sucrase and phosphatase at maturity under DS were all higher than that under both Control and CS. In addition, soil organic matter (SOM) and total nitrogen (TN) under DS and DFS were 20~26% and 11~12% higher than that under B and DF respectively, suggesting straw addition could benefit paddy soil quality. Moreover, coupling straw and digestate would contribute to decrease the N content in soil surface water. Overall, our results demonstrated that digestate and straw combined application could maintain rice production and have potential positive paddy environmental effects.

Yield Variation Characteristics of Red Paddy Soil under Long-Term Green Manure Cultivation and Its Influencing Factors

“…Notably, the analyses performed herein indicate that there were no significant differences between the combined inorganic fertilizer plus Chinese milk vetch treatments and pure inorganic fertilizer (NPK) on yield. Several studies [ 3 , 12 , 14 ] reported similar conclusions, wherein they showed that combinations of chemical and organic fertilizers do not enhance rice yields more than chemical fertilizers alone. This may be attributed to the relatively high proportion of chemical fertilizers used in the combined treatments, which masks the benefits of organic fertilizers and undermines their persistent and slow-acting effects [ 12 , 22 ].…”

“…As a major rice-producing region in the south, the Jiangxi Province is ranked second and third in China in the rice cultivation area and total yield, respectively [ 2 ]. Of the 1.28 million km 2 used to grow rice in southern China, 300,000 km 2 (16%) are primarily composed of red paddy soil and produce 50% of China’s total rice yield [ 3 , 4 ]. Thus, the red paddy field is an important soil resource of China and plays a crucial role in maintaining food security [ 1 , 3 , 4 ].…”

“…Of the 1.28 million km 2 used to grow rice in southern China, 300,000 km 2 (16%) are primarily composed of red paddy soil and produce 50% of China’s total rice yield [ 3 , 4 ]. Thus, the red paddy field is an important soil resource of China and plays a crucial role in maintaining food security [ 1 , 3 , 4 ].…”

A preliminary report of integrating sheep farming in combination with adopting biogas technology in organic rice farming systems in upland areas in Indonesia

“…The biogas technology provides energy and produces digestate, which contains microbial biomass, metabolic compounds, and complex organic structures and can be used as an organic fertilizer (Bonten et al, 2014;González et al, 2021;Kebede et al, 2023). The use of digestate as organic fertilizer for the rice field has been shown in the study of Hu et al (2021). They demonstrated that coupled digestate and straw application could maintain rice production and have potential positive rice environmental effects.…”