Growth, Nitrogen and Phosphorus Uptake of Sorghum Plants as Affected by Green Manuring with Pea or Faba Bean Shell Pod Wastes Using 15N

Abstract

Background: During the freezing or canning preparation process of green grain leguminous, large amounts of shell pods are considered as agricultural organic wastes, which may be used as Green Manure (GM) for plant growth enhancement. Objective: Evaluation of the effectiveness of soil amended with shell pod wastes of pea (PGM) or faba bean (FGM) as GM on growth, nitrogen and phosphorus uptake in sorghum plants. Methods: Determination of the impact of adding four rates of nitrogen (0, 50, 100, and 150 kg N ha-1) in the form of pea (PGM) or faba bean (FGM) shell pod wastes as GM on the performance of sorghum using the indirect 15N isotopic dilution technique. Results: Sorghum plants responded positively and differently to the soil amendments with either GMs used, particularly, the PGM. In comparison with the control (N0), soil amendment with an equivalent rate of 3.5 t ha-1 of PGM (PGM100) or with 6.5 t ha-1 of FGM (FGM150) almost doubled dry weight, N and P uptake in different plant parts of sorghum. Regardless of the GM used, estimated values of %Ndfgm in sorghum plants ranged from 35% to 55% indicating that the use of pod shells as GM provided substantial portions and amounts of N requirements for sorghum. Moreover, nitrogen recoveries of added GM (%NUEgm) ranged from 29 to 45% indicating that N in both of GM forms were used effectively. Accordingly, equivalent amounts to 17 - 48 kg N ha-1 of inorganic fertilizer may be saved. The beneficial effect of incorporating pod shells in soil on sorghum N was mainly attributed to their N availability, besides to their effects on the improvement of soil N uptake, particularly when using PGM. Conclusion: The agricultural by-products of faba bean and pea pod shells could be used as GM for sorghum growth improvement by enhancing N and P uptake from soil and from the organic source.

Agri-Food Waste as a Method for Weed Control and Soil Amendment in Crops

“…One plausible explanation for the reduced weed growth found in CC pots may be related to the C/N ratio and the lower nutrient content of this raw waste compared to CG and F (Table S1). The C/N ratios for CG and F are around 23:1 and 18:1, respectively [33,37]. However, CC has a C/N ratio of 120:1 [50], which is very high, explaining its poor quality.…”

“…Similarly, Chrysargyris et al [54] found that a substrate mixture including CG showed enriched content of N, P, K, and some micronutrients. In the case of F waste, Al-Chammaa et al [37] proved that adding green manures of V. faba pods as soil amendment with, 15 days before plant sowing, provided a considerable amount of N requirements for Sorghum plants. These three studies were conducted in pots using a range of substrates (peat-perlite and field soil).…”

“…Interestingly, fresh flowering V. faba plants incorporated into the soil reduced weed biomass in maize crops by 50% in the short-term, but increased crop and weed biomass after the phytotoxic effects disappeared [36]. For V. faba pod waste in particular, Al-Chammaa et al [37] found that sorghum plants almost doubled their biomass in response to soil amendments with this type of green manure, with the N from green manure being effectively used (up to 45%) by sorghum. Pod-waste extracts are known to have phytotoxic activity on three nematode species under in vitro and in vivo conditions [38].…”

Regulation of photosynthetic material production by inter-root microbial extinction and metabolic pathways in sorghum under different nitrogen application patterns

“…The richest habitat for biodiversity on earth is the soil, which is rich in organic and inorganic material that provides habitat for various biological communities 16 , 17 . Soil microorganisms are involved in ecological processes such as nutrient decomposition and supply, and they are an essential component of growth and yield formation 18 .…”