Evaluation of sowing methods and nitrogen levels for grain yield and components of durum wheat under arid region of Egypt

The present experiment was conducted at private farm during 2018/19 and 2019/20 seasons. The investigated area lies within the extremely arid belt, having long hot summer and short warm winter. The main goal of this investigation was to evaluate the effect of different sowing methods on yield components of wheat, using split plot design with three replications. Sowing methods in main plot were broadcasting method, row spacing 10, 15 and 20 cm apart). Nitrogen fertilizer levels in sub plot were 60, 75 and 90 kg N fed-1 (fed = 4200 m-2). The increase percentage due to row spacing at 20 cm apart (M4) compared to broadcasting method (M1) were (23.30 & 26.74%) for spike length; (5.11 & 6.94 %) for 1000 grain weight and (8.02 & 7.74%) for grain yield and according ally (3.07 & 3.08%) for harvest index in both seasons, respectively. Overall, from the present study the sowing method in rows with 20 cm apart and the optimum N fertilizer rate (90 kg fed-1) for durum wheat production in the soils of Qasir, Dakhala oasis on silt loam soil was the best treatment.

Extreme Weather Events Affect Agronomic Practices and Their Environmental Impact in Maize Cultivation

Sustainable and profitable crop production has become a challenge due to frequent weather extremes, where unstable crop yields are often followed by the negative impacts of agronomic practices on the environment, i.e., nitrate leaching in irrigated and nitrogen (N)-fertilized crop production. To study this issue, a three-year field study was conducted during quite different growing seasons in terms of weather conditions, i.e., extremely wet, extremely dry, and average years. Over three consecutive years, the irrigation and N fertilizers rates were tested for their effect on grain yield and composition, i.e., protein, starch, and oil content of the maize hybrids; soil N level (%); and nitrate leaching. The results showed that the impact of the tested factors and their significance was year- or weather-condition-dependent. The grain yield result stood out during the extremely wet year, where the irrigation rate reduced the grain yield by 7.6% due to the stress caused by the excessive amount of water. In the remainder of the study, the irrigation rate expectedly increased the grain yield by 13.9% (a2) and 20.8% (a3) in the extremely dry year and 22.7% (a2) and 39.5% (a3) during the average year. Regardless of the weather conditions, the N fertilizer rate increased the grain yield and protein content. The soil N level showed a typical pattern, where the maximum levels were at the beginning of the study period and were higher as the N fertilizer rate was increased. Significant variations in the soil N level were found between weather conditions (r = −0.719) and N fertilizer rate (r = 0.401). Nitrate leaching losses were expectedly found for irrigation and N fertilizer treatments with the highest rates (a3b3 = 79.8 mg NO3− L).

Effect of nitrogen fertilization on maize yield responses to soil microbial activity and root length density in the North China Plain

A maize field experiment in the North China Plain was conducted to understand the effect of different N fertilizer rate on the yield of maize, using soil microbial activity and root length density (RLD) as performance parameters, due to their possibility to enhance productivity. The four N fertilizer rates were 0 (N0), 120 (N120), 210 (N210) and 300 (N300) kg N hm-2. The results indicated that nitrogen (N) fertilizer had a significant influence not only on yield (p<0.05), but also on root length density (p<0.05) and soil microbial activity (p<0.05). In addition, the soil microbial activity and RLD were significantly related with maize yield. RLD differences were generally evident within the 100 cm soil layer, whereas there was no difference in the deeper soil under different N treatments. The most RLD concentrated in 0-60cm soil layer under N0, N120 and in 0-90cm soil layer under N210, N300. The microbial growth rate constant (k) was greater in N210 than other treatments. Generally, N fertilizer application can stimulate root growth and microbial activity, meanwhile, they can interact with each other, heighten the availability of N fertilizer in soil, thus enhanced yield of maize. According to our study, 210 kg N hm-2 was the optimum N fertilizer rate to achieve maximum yield and sustain the soil productivity.

Strip width ratio expansion with lowered N fertilizer rate enhances N complementary use between intercropped pea and maize

Maize (Zea mays L.)/pea (Pisum sativum L.) strip intercropping is considered a promising cropping system to boost crop productivity. The 3-year (2009–2011) field experiment was conducted at Wuwei, northwest China, with two maize to pea strip width ratios (80:80 cm and 120:80 cm), each under three N fertilizer rates (0, 90 and 135 kg N ha−1 for pea, and 0, 300, and 450 kg N ha−1 for maize). The results showed that expanding maize to pea strip width ratio from 80:80 cm to 120:80 cm coupled with a reduction of N fertilizer rate intensified N competition and improved N compensation. The apparent N recovery and N utilization efficiency of intercropped pea with strip width ratio of 120:80 cm were increased by 8.0% and 8.9% compared to strip width ratio of 80:80 cm. Compared to high N rate, the two indicators of intercropped pea with lowered N rate were increased by 10.0% and 6.0%. For intercropped maize, the two indicators were increased by 6.8% and 5.1%, with strip width ratio of 120:80 cm compared to 80:80 cm. Also, they were improved by 9.7% and 11.5%, with lowered N rate compared to high N rate. Consequently, the grain yield of pea and maize in the 120:80 cm pattern was improved by 11.9% and 7.7% compared to 80:80 cm. We concluded that expanding maize to pea strip ratio coupled with N fertilizer reduction can optimize N complementary use.

Effect of reduced nitrogen fertilizer rate on nitrogen uptake and yield of spinach (Amaranthus spp.)

Reducing nitrogen (N) fertilizer rate have beneficial effect on N uptake by plants. Studies on reducing N rate in sweet potato and beetroot to improve their growth and yield are well documented but the effect of decreased N rate on N uptake by leafy vegetables are limited. A glasshouse experiment was conducted to determine the effect of different N rate on N uptake of green spinach. Treatments evaluated were (i) soil alone, and (ii) different N fertilizer rate (12, 24, 36, 60, 90 and 120 kg N/ha). Treatments were applied at 14 days after seeding (DAS) at a uniform rate of 2 t/ha. Results revealed that moderate N input between 12 to 36 kg N/ha improved N uptake and yield of spinach compared with lower rate of N input (0 to 12 kg N/ha) but higher N level of 90 kg N/ha was most effective in improving N uptake and fresh yield. The effectiveness of N input at 90 kg N/ha corresponded to the optimum retention of soil N resulting in timely availability of N for uptake by spinach leading to higher yield. Although treatment with excess N (120 kg N/ha) improved N uptake, the decline in yield was because of soil nutrient imbalance that inhibited other nutrients required by plants for growth and development. The findings from the study suggest that reducing N fertilizer rate improves N uptake in leafy vegetables without reducing productivity depending on their specific N requirement.

Camelina and Crambe Oil Crops for Bioeconomy—Straw Utilisation for Energy

Agriculture can provide biomass for bioproducts, biofuels and as energy feedstock with a low environmental impact, derived from carbohydrate, protein and oil annual crops, as well from lignocellulosic crops. This paper presents the thermophysical and chemical features of camelina and crambe straw depending on nitrogen fertilisation rate with a view to their further use in a circular bioeconomy. A two-factorial field experiment was set up in 2016, with camelina and crambe as the first factor and the N fertilizer rate (0, 60 and 120 kg·ha−1·N) as the second factor. Ash content in crambe straw (6.97% d.m.) was significantly higher than in camelina straw (4.79% d.m.). The higher heating value was higher for the camelina (18.50 MJ·kg−1·d.m.) than for the crambe straw (17.94 MJ·kg−1·d.m.). Sulphur content was also significantly higher in camelina than in crambe straw. An increase in nitrogen content with increasing fertilisation rate was visible in the straw of both species (from 1.19 to 1.33% d.m., for no fertilisation and for a rate of 120 kg·ha−1·N, respectively). Crambe straw contained more than five times more chlorine than camelina straw. In conclusion, despite certain adverse properties, camelina and crambe straw can be an alternative to other types of biomass, both for direct combustion, gasification and in the production of second-generation biofuels.

An integrative influence of saline water irrigation and fertilization on the structure of soil bacterial communities

Although numerous studies have investigated the individual effects of salinity, irrigation and fertilization on soil microbial communities, relatively less attention has been paid to their combined influences, especially using molecular techniques. Based on the field of orthogonal designed test and deoxyribonucleic acid sequencing technology, the effects of saline water irrigation amount, salinity level of irrigation water and nitrogen (N) fertilizer rate on soil bacterial community structure were investigated. The results showed that the irrigation amount was the most dominant factor in determining the bacterial richness and diversity, followed by the irrigation water salinity and N fertilizer rate. The values of Chao1 estimator, abundance-based coverage estimator and Shannon indices decreased with an increase in irrigation amount while increased and then decreased with an increase in irrigation water salinity and N fertilizer rate. The highest soil bacterial richness and diversity were obtained under the least irrigation amount (25 mm), medium irrigation water salinity (4.75 dS/m) and medium N fertilizer rate (350 kg/ha). However, different bacterial phyla were found to respond distinctively to these three factors: irrigation amount significantly affected the relative abundances of Proteobacteria and Chloroflexi; irrigation water salinity mostly affected the members of Actinobacteria, Gemmatimonadetes and Acidobacteria; and N fertilizer rate mainly influenced the Bacteroidetes' abundance. The results presented here revealed that the assessment of soil microbial processes under combined irrigation and fertilization treatments needed to be more careful as more variable consequences would be established by comparing with the influences based on an individual factor, such as irrigation amount or N fertilizer rate.