A large number of studies show that the utilization rate of chemical fertilizer in agricultural production in that season is only 30% ~ 35%. The loss of chemical fertilizer is a very serious problem, which not only causes economic losses, but also intensifies the eutrophication of water body. Therefore, the most noteworthy thing is to improve the utilization efficiency of fertilizer, make full use of water and fertilizer in waste baby diapers, reduce or avoid fertilizer pollution, and develop sustainable and efficient agriculture.
We know that the bioavailability of water absorbent and its adsorbed water and fertilizer in baby diapers does exist. It was found that with the increase of the amount of waste products, the relative growth height of plants, the accumulation of plant dry matter, the weight and length of plant dry roots changed significantly, indicating that it is effective in maintaining nutrition. On the one hand, when the soil nutrients are sufficient, the baby's diapers absorb nutrients and play a role in preservation. on the other hand. Plant growth requires soil to provide nutrients, and the products slowly release the adsorbed nutrients to plants.
The control of initial fertilization is the same. Under three different addition methods, the content of hydrolyzed nitrogen in soil changed significantly. Compared with the blank, the content of hydrolyzed nitrogen increased. When the addition amount exceeds 0.6%, the content of hydrolyzed nitrogen is: mixing > burying > external paving. When the addition amount was more than 0.2%, the change of hydrolyzed silkworm content was more obvious in the mixing and burial mode than in the spreading mode. With the increase of gradient, the hydrolyzed nitrogen increased more than twice. After sufficient nitrogen fertilizer is put into the diaper, it will be more active for the baby to hydrolyze nitrogen directly. On the one hand, after adding diapers, soil moisture and pore structure are more conducive to the biological living environment.
The absorption of water and fertilizer in baby diapers has a significant effect on plant growth. When the dosage is controlled to 0.8%, the baby diapers adsorbed with different water and fertilizer contents are put into the soil respectively, and the hydrolyzed nitrogen content is measured. In these three modes, only in the mixed mode, the change of hydrolyzed nitrogen is more obvious. At this time, the change trend of hydrolyzed nitrogen was similar in the outer paving and burial modes. The reason for this change can be attributed to the fact that in the mixed mode, the soil is directly affected by water and fertilizer. In the outer burial mode, crops may not use water and fertilizer. In the mode of spreading and burying, it has little effect on the physical and chemical properties, structure and microbial activity.
Ammonia volatilization and leaching loss of nitrogen are the main reasons for nitrogen loss. Urea dissolves and hydrolyzes in soil. Ammonia in soil is easy to volatilize and lose in a short time. Adding baby diapers to the soil can effectively adsorb urea molecules and hydrolysates dissolved in the soil.
This is closely related to the network structure and properties of water retaining agent: when the water retaining agent expands, the network structure of polymer crosslinking can diffuse some small molecules or ions. The nutritional ions entering the molecule mainly have the following directions: 1. Wrapped in expanded water retaining agent molecules; 2. Temporarily fixed by ion adsorption, ion exchange, van der Waals force, electrostatic attraction, aohe and other mechanisms; 3. Delay the release of nutrients.
Other studies have shown that the water retaining agent in baby diapers interacts with two different active groups on the surface of soil particles. Create a stable particle structure of effluent and absorb nutrients, so as to inhibit nutrient loss.